NORTHWESTERN MUTUAL LIFE INSURANCE CO
10-K, 1998-07-14
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<PAGE>   1
                       SECURITIES AND EXCHANGE COMMISSION
                            Washington, D.C.  20549

                                   Form 10-K

                ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF
                      THE SECURITIES EXCHANGE ACT OF 1934

For the fiscal year ended December 31, 1997  Commission file numbers 2-64683,
2-94234 and 2-89905.

                THE NORTHWESTERN MUTUAL LIFE INSURANCE COMPANY
            ------------------------------------------------------
            (Exact name of Registrant as specified in its Charter)


               Wisconsin                             39-0509570
- ----------------------------------------  ---------------------------------
    (State or other jurisdiction of               (I.R.S. Employer
     incorporation or organization)              Identification No.)
       720 East Wisconsin Avenue

          Milwaukee, Wisconsin                          53202
- ----------------------------------------  ---------------------------------
(Address of principal executive offices)             (Zip Code)

Registrant's telephone number, including area code:   414/271-1444
                                                     ------------------

Securities registered pursuant to Section 12(b) of the Act:

                                              Name of each exchange on
          Title of each class                     which registered
         ---------------------                ------------------------
                  None                                  None

        Securities registered pursuant to Section 23(g) of the Act:

                                   None
                                   ----

     "Indicate by check mark whether the Registrant (1) has filed all reports
required to be filed by Section 13 or 15(d) of the Securities Exchange Act of
1934 during the preceding 12 months (or for such shorter period that the
Registrant was required to file such reports), and (2) has been subject to such
filing requirements for the past 90 days.  Yes   X      No     ."
                                               -----       ----

     "State the aggregate market value of the voting stock held by
non-affiliates of the Registrant. The aggregate market value shall be computed
by reference to the price at which the stock was sold or the average bid and
asked prices of such stock, as of a specified date within 60 days prior to the
date of filing.  (See definition of affiliate in Rule 405.)"

                                 Not Applicable

     "Indicate the number of shares outstanding of each of the issuer's classes
of common stock, as of the latest practicable date."

                                      None

                     "DOCUMENTS INCORPORATED BY REFERENCE"
                                      None

                    This Form 10-K report contains 66 pages.

                    The Exhibit Index is located on page 42.



<PAGE>   2

                 The Northwestern Mutual Life Insurance Company
                                   Form 10-K


                                     PART I

Item 1. Business

            (a)   General development of business.

                  There have been no material changes or developments since the
                  beginning of the fiscal year in the business done or intended
                  to be done by the Registrant and its subsidiaries.

            (b)   Financial information about industry segments.

                  The registrant is a mutual life insurance company whose
                  principal product is life insurance.  The Registrant also
                  sells annuity contracts, including variable annuity
                  contracts.

            (c)   Description of business.

                  The Registrant is the fifth largest life insurance company in
                  the United States with total assets in excess of $71 billion
                  on December 31, 1997.

                  The Registrant's principal products are life insurance
                  contracts distributed by approximately 6,000 full-time
                  producing agents.  Sales of life insurance contracts as a
                  percentage of total sales is as follows:


                           1997         81.43%
                           1996         80.78%
                           1995         81.22%
                           1994         80.60%
                           1993         82.44%
                           1992         81.44%
                           1991         81.11%
                           1990         82.64%
                           1989         83.12%
                           1988         84.18%


                  As of December 31, 1997, the Registrant had 3,818 employees.

            (d)   Not applicable.



Item 2.  Properties

             The principal properties used in the business are located at 720
             East Wisconsin Avenue and 818 East Mason Street, Milwaukee,
             Wisconsin.  The properties, which house the Registrant's home
             office, include approximately three and one-half square blocks
             improved with three office buildings and a parking structure. 
             Title to land and buildings is held in fee. 


                              Item 3 is on page 3.

                                                                              2

<PAGE>   3

                 The Northwestern Mutual Life Insurance Company
                                   Form 10-K



Item 3. Legal Proceedings

            The Northwestern Mutual Life Insurance Company is engaged in
            litigation of various kinds, which in its judgment is not of
            material importance in relation to its total assets.  The
            litigation includes various administrative or judicial proceedings,
            relating to investments of the Registrant, arising under Federal,
            State or local provisions that have been enacted or adopted
            regulating the discharge of materials into the environment or
            primarily for the purpose of protecting the environment.  The
            Registrant believes that these proceedings, singly and in the
            aggregate, are not material.  In addition, NML Variable Annuity
            Accounts A and C are not engaged in any litigation which is
            considered material to their total assets.

Item 4. Submission of Matters to a Vote of Security Holders

            (a)  Not applicable.  The Registrant is a mutual life
                 insurance company and has no stockholders as such.

            (b)  Not applicable.

            (c)  Not applicable.

            (d)  Not applicable.



                              Item 5 is on page 4.



                                                                              3
<PAGE>   4

                 The Northwestern Mutual Life Insurance Company
                                   Form 10-K



                                    PART II

Item 5. Market for the Registrant's Common Stock and Related Stockholder
        Matters

            (a)  Not applicable.  The Registrant is a mutual life
                 insurance company and has no equity securities or stockholders
                 as such.

            (b)  Not applicable.

            (c)  Not applicable.



                              Item 6 is on page 5.



                                                                               4
<PAGE>   5




                 The Northwestern Mutual Life Insurance Company
                                    Form 10-K

Item 6.    Selected Financial Data

           Results of Operations for NML Variable Annuity Account A for each of
the five years ending December 31, follows:

<TABLE>
<CAPTION>
                                                                             1997           1996           1995            1994    
                                                                        ------------   ------------   ------------    ------------
<S>                                                                     <C>            <C>            <C>            <C>         
Investment Income

     Dividend Income from Northwestern Mutual Series Fund, Inc.
       Aggressive Growth Stock Portfolio ............................   $  5,046,819   $  2,456,762   $    256,787   $    248,438

     Dividend Income from Northwestern Mutual Series Fund, Inc.      
       International Equity Portfolio ...............................      1,627,765      1,820,972        217,966        853,704

     Dividend Income from Northwestern Mutual Series Fund, Inc.      
       Growth Stock Portfolio .......................................        769,950        379,453        128,854         18,971##

     Dividend Income from Northwestern Mutual Series Fund, Inc.       
       Growth and Income Stock Portfolio ............................      5,154,785      1,206,606        465,091         53,075##

     Dividend Income from Northwestern Mutual Series Fund, Inc. Index
       500 Stock Portfolio ..........................................      3,229,605      1,906,168        522,842      2,155,181

     Dividend Income from Northwestern Mutual Series Fund, Inc.      
       Balanced Portfolio ...........................................     13,244,993     14,325,426      8,146,698     33,071,685

     Dividend Income from Northwestern Mutual Series Fund, Inc. High
       Yield Bond Portfolio .........................................      1,418,106        473,729        199,805         68,840##

     Dividend Income from Northwestern Mutual Series Fund, Inc.       
       Select Bond Portfolio ........................................      1,556,695        906,892        652,667      2,990,731

     Dividend Income from Northwestern Mutual Series Fund, Inc. Money
       Market Portfolio .............................................      1,203,410      1,024,534      1,119,254        708,559

     Dividend Income from Northwestern Mutual Capital
       Appreciation Stock Fund, Inc. ................................             NA             NA             NA             NA
                                                                        ------------   ------------   ------------   ------------

       Total Income .................................................     33,252,128     24,500,542     11,709,964     40,169,184



     Annuity Rate and Expense Guarantees ............................      7,048,888      5,783,739      5,072,064      4,466,142
                                                                        ------------   ------------   ------------   ------------

     Net Investment Income ..........................................   $ 26,203,240   $ 18,716,803   $  6,637,900   $ 35,703,042
                                                                        ============   ============   ============   ============


Realized and Unrealized Gain (Loss) on Investments

     Realized Gain on Investments ...................................   $ 23,135,675   $ 13,967,988   $ 13,141,169   $  1,687,702

     Unrealized Appreciation (Depreciation) of Investments During the
       Year .........................................................     56,364,111     33,051,905     76,916,515    (39,969,923)
                                                                        ------------   ------------   ------------   ------------

     Net Gain (Loss) on Investments .................................   $ 79,499,786   $ 47,019,893   $ 90,057,684   ($38,282,221)
                                                                        ============   ============   ============   ============


<CAPTION>

                                                                             1993
                                                                        ------------
<S>                                                                     <C>         
     Dividend Income from Northwestern Mutual Series Fund, Inc.
       Aggressive Growth Stock Portfolio ............................   $    359,370
     Dividend Income from Northwestern Mutual Series Fund, Inc.      
       International Equity Portfolio ...............................         97,043#

     Dividend Income from Northwestern Mutual Series Fund, Inc.      
       Growth Stock Portfolio .......................................             NA

     Dividend Income from Northwestern Mutual Series Fund, Inc.       
       Growth and Income Stock Portfolio ............................             NA

     Dividend Income from Northwestern Mutual Series Fund, Inc. Index
       500 Stock Portfolio ..........................................        256,688

     Dividend Income from Northwestern Mutual Series Fund, Inc.      
       Balanced Portfolio ...........................................     13,161,961

     Dividend Income from Northwestern Mutual Series Fund, Inc. High
       Yield Bond Portfolio .........................................             NA

     Dividend Income from Northwestern Mutual Series Fund, Inc.       
       Select Bond Portfolio ........................................      1,423,472

     Dividend Income from Northwestern Mutual Series Fund, Inc. Money
       Market Portfolio .............................................        520,596

     Dividend Income from Northwestern Mutual Capital
       Appreciation Stock Fund, Inc. ................................        976,621**
                                                                        ------------

       Total Income .................................................     16,795,751



     Annuity Rate and Expense Guarantees ............................      4,074,129
                                                                        ------------

     Net Investment Income ..........................................   $  2,721,622
                                                                        ============

Realized and Unrealized Gain (Loss) on Investments

     Realized Gain on Investments ...................................   $  2,347,432

     Unrealized Appreciation (Depreciation) of Investments During the
       Year .........................................................     14,612,044
                                                                        ------------

     Net Gain (Loss) on Investments .................................   $ 16,959,476
                                                                        ============


</TABLE>


**   Represents operations through April 29, 1993.
 #   Commenced operations on April 30, 1993.
##   Commenced operations on May 3, 1994.

                See Notes to Financial Statements on page 22-23.
                                                                               5

<PAGE>   6


Item 6.    (continued)

          Changes in Equity for NML Variable  Annuity  Account A for each of the
     five years ending December 31, follows:

<TABLE>
<CAPTION>
                                                                          1997             1996              1995             
                                                                      -------------    -------------    --------------
<S>                                                                   <C>              <C>              <C>          
From Investment Activities
     Net Investment Income ........................................   $  26,203,240    $  18,716,803    $   6,637,900

     Net Realized Gain on Investments .............................      23,135,675       13,967,988       13,141,169

     Net Change in Unrealized Appreciation (Depreciation) of
       Investments ................................................      56,364,111       33,051,905       76,916,515
                                                                      -------------    -------------    -------------

              Increase (Decrease) in Equity Derived from Investment
                Activities ........................................     105,703,026       65,736,696       96,695,584
                                                                      -------------    -------------    -------------

From Equity Transactions

     Contract Owners' Net Payments ................................      61,964,558       65,169,358       49,124,853

     Annuity Payments .............................................      (1,046,956)        (830,996)        (610,983)

     Surrenders and Other (Net) ...................................     (65,746,579)     (52,376,445)     (62,309,189)
                                                                      -------------    -------------    -------------

              Increase (Decrease) in Equity Derived from Equity
                Transactions ......................................      (4,828,977)      11,961,917      (13,795,319)
                                                                      -------------    -------------    -------------

Net Increase (Decrease) in Equity .................................     100,874,049       77,698,613       82,900,265

Equity, Beginning of Year .........................................     547,520,040      469,821,427      386,921,162
                                                                      -------------    -------------    -------------

Equity, End of Year ...............................................   $ 648,394,089    $ 547,520,040    $ 469,821,427
                                                                      =============    =============    =============



<CAPTION>
                                                                          1994              1993   
                                                                      -------------    -------------  
<S>                                                                   <C>              <C>          
From Investment Activities
     Net Investment Income ........................................   $  35,703,042    $  12,721,622

     Net Realized Gain on Investments .............................       1,687,702        2,347,432

     Net Change in Unrealized Appreciation (Depreciation) of
       Investments ................................................     (39,969,923)      14,612,044
                                                                      -------------    -------------

              Increase (Decrease) in Equity Derived from Investment
                Activities ........................................      (2,579,179)      29,681,098
                                                                      -------------    -------------

From Equity Transactions

     Contract Owners' Net Payments ................................      52,262,816       51,044,522

     Annuity Payments .............................................        (603,158)        (522,956)

     Surrenders and Other (Net) ...................................     (33,008,630)     (33,141,406)
                                                                      -------------    -------------

              Increase (Decrease) in Equity Derived from Equity
                Transactions ......................................      18,651,028       17,380,160
                                                                      -------------    -------------

Net Increase (Decrease) in Equity .................................      16,071,849       47,061,258

Equity, Beginning of Year .........................................     370,849,313      323,788,055
                                                                      -------------    -------------

Equity, End of Year ...............................................   $ 386,921,162    $ 370,849,313
                                                                      =============    =============
</TABLE>


                See Notes to Financial Statements on page 22-23.

                                                                               6
<PAGE>   7


Item 6.    (continued)

          Total  Assets of NML Variable  Annuity  Account A for each of the five
     following years at December 31, follows:

<TABLE>
<CAPTION>
                                                                             1997         1996             1995    
                                                                        -------------  ------------    ------------
<S>                                                                     <C>            <C>            <C>         
Assets
     Investments at Market Value:

         Northwestern Mutual Series Fund, Inc. Aggressive Growth
           Stock Portfolio ..........................................   $ 89,428,723   $ 78,087,972   $ 56,491,009

         Northwestern Mutual Series Fund, Inc. International Equity
           Portfolio ................................................     50,148,435     41,497,787     31,789,148

         Northwestern Mutual Series Fund, Inc. Growth Stock 
           Portfolio ................................................     17,260,514      9,523,179      4,284,669

         Northwestern Mutual Series Fund, Inc. Growth and Income
           Stock Portfolio ..........................................     23,575,574     13,199,558      7,891,655

         Northwestern Mutual Series Fund, Inc. Index 500 Stock
           Portfolio ................................................    111,140,823     80,917,025     62,391,687

                                                                 
         Northwestern Mutual Series Fund, Inc. Balanced Portfolio....    302,749,909    270,745,111    257,867,967

         Northwestern Mutual Series Fund, Inc. High Yield Bond
           Portfolio ................................................      8,743,385      4,907,490      2,060,076

         Northwestern Mutual Series Fund, Inc. Select Bond
           Portfolio ................................................     25,252,973     26,648,961     25,742,752

                                                                     
         Northwestern Mutual Series Fund, Inc. Money Market Portfolio     21,586,115     23,380,205     21,556,895

Due from NML Insurance Company ......................................        322,747        123,152        491,572

Due from Sale of Fund Shares ........................................      1,555,441        387,086         78,037
                                                                        ------------   ------------   ------------

           Total Assets .............................................   $651,764,639   $549,417,526   $470,645,467
                                                                        ============   ============   ============


<CAPTION>


                                                                            1994           1993
                                                                        ------------   ------------
<S>                                                                     <C>            <C>         
         Northwestern Mutual Series Fund, Inc. Aggressive Growth
           Stock Portfolio ..........................................   $ 36,256,480   $ 22,946,546

         Northwestern Mutual Series Fund, Inc. International Equity
           Portfolio ................................................     28,832,978     11,844,559#

         Northwestern Mutual Series Fund, Inc. Growth Stock 
           Portfolio ................................................      1,397,703##           NA

         Northwestern Mutual Series Fund, Inc. Growth and Income
           Stock Portfolio ..........................................      3,282,764##           NA

         Northwestern Mutual Series Fund, Inc. Index 500 Stock
           Portfolio ................................................     43,545,408     43,534,827

         Northwestern Mutual Series Fund, Inc. Balanced Portfolio....    230,871,659    252,635,446
         Northwestern Mutual Series Fund, Inc. High Yield Bond
           Portfolio ................................................      1,242,382##           NA

         Northwestern Mutual Series Fund, Inc. Select Bond
           Portfolio ................................................     22,258,901     24,004,669

         Northwestern Mutual Series Fund, Inc. Money Market 
           Portfolio.................................................     20,120,832     17,036,899
Due from NML Insurance Company ......................................        179,152        182,546

Due from Sale of Fund Shares ........................................        319,392        418,356
                                                                        ------------   ------------

           Total Assets .............................................   $388,307,651   $372,603,848
                                                                        ============   ============

</TABLE>


#    Commenced operations on April 30, 1993.
##   Commenced operations on May 3, 1994.


                See Notes to Financial Statements on page 22-23.

                                                                               7

<PAGE>   8


Item 6.    (continued)

     Results of Operations  for NML Variable  Annuity  Account C for each of the
five years ending December 31, follows:

<TABLE>
<CAPTION>
                                                                           1997           1996            1995             
                                                                       ------------   ------------   --------------        
<S>                                                                    <C>            <C>            <C>         
Investment Income

     Dividend Income from Northwestern Mutual Series Fund, Inc. 
       Aggressive Growth Stock Portfolio ...........................   $  6,049,655   $  2,574,462   $    242,583

     Dividend Income from Northwestern Mutual Series Fund, Inc.     
       International Equity Portfolio ..............................      1,945,549      1,805,160        190,138

     Dividend Income from Northwestern Mutual Series Fund, Inc.      
       Growth Stock Portfolio ......................................        712,380        366,920         59,271

     Dividend Income from Northwestern Mutual Series Fund, Inc.      
       Growth and Income Stock Portfolio ...........................      5,940,640      1,146,200        276,923

     Dividend Income from Northwestern Mutual Series Fund, Inc.     
       Index 500 Stock Portfolio ...................................      3,755,769      2,082,261        544,553

     Dividend Income from Northwestern Mutual Series Fund, Inc.      
       Balanced Portfolio ..........................................      6,460,653      7,534,370      4,212,478

     Dividend Income from Northwestern Mutual Series Fund, Inc. High
       Yield Bond Portfolio ........................................      1,028,027        309,003         55,220

     Dividend Income from Northwestern Mutual Series Fund, Inc.     
       Select Bond Portfolio .......................................      1,057,558        566,451        395,357

     Dividend Income from Northwestern Mutual Series Fund, Inc.     
       Money Market Portfolio ......................................        738,932        609,543        494,253

     Dividend Income from Northwestern Mutual Capital Appreciation
       Stock Fund, Inc. ............................................             NA             NA             NA
                                                                       ------------   ------------   ------------

                  Total Income .....................................     27,689,163     16,994,370      6,470,776

     Annuity Rate and Expense Guarantees ...........................      2,501,975      1,738,625        856,764
                                                                       ------------   ------------   ------------

     Net Investment Income .........................................   $ 25,187,188   $ 15,255,745   $  5,614,012
                                                                       ============   ============   ============

Realized and Unrealized Gain (Loss) on Investments

     Realized Gain on Investments ..................................   $ 18,686,284   $  8,855,390   $  9,884,364

     Unrealized Appreciation (Depreciation) of Investments During
       the Year ....................................................     44,241,434     29,832,124     53,407,857
                                                                       ------------   ------------   ------------

     Net Gain (Loss) on Investments ................................   $ 62,927,718   $ 38,687,514   $ 63,292,221
                                                                       ============   ============   ============


<CAPTION>

                                                                            1994            1993
                                                                       ------------    -------------
<S>                                                                    <C>             <C>         
     Dividend Income from Northwestern Mutual Series Fund, Inc.
       Aggressive Growth Stock Portfolio ...........................   $    232,345    $    342,725

     Dividend Income from Northwestern Mutual Series Fund, Inc.      
       International Equity Portfolio ..............................        703,931          26,336#

     Dividend Income from Northwestern Mutual Series Fund, Inc.      
       Growth Stock Portfolio ......................................          4,518##            NA

     Dividend Income from Northwestern Mutual Series Fund, Inc.      
       Growth and Income Stock Portfolio ...........................         19,233##            NA

     Dividend Income from Northwestern Mutual Series Fund, Inc.     
       Index 500 Stock Portfolio ...................................      2,226,240         260,710

     Dividend Income from Northwestern Mutual Series Fund, Inc.      
       Balanced Portfolio ..........................................     17,046,665       6,769,160

     Dividend Income from Northwestern Mutual Series Fund, Inc. High
       Yield Bond Portfolio ........................................         11,456 ##           NA

     Dividend Income from Northwestern Mutual Series Fund, Inc.      
       Select Bond Portfolio .......................................      1,874,182         813,051

     Dividend Income from Northwestern Mutual Series Fund, Inc.      
       Money Market Portfolio ......................................        443,639         269,586

     Dividend Income from Northwestern Mutual Capital Appreciation
       Stock Fund, Inc. ............................................             NA       1,078,208 **
                                                                       ------------    ------------

                  Total Income .....................................     22,562,209       9,559,776

     Annuity Rate and Expense Guarantees ...........................        509,648         235,930
                                                                       ------------    ------------

     Net Investment Income .........................................   $ 22,052,561    $  9,323,846
                                                                       ============    ============

Realized and Unrealized Gain (Loss) on Investments

     Realized Gain on Investments ..................................   $  5,949,795    $  3,670,743

     Unrealized Appreciation (Depreciation) of Investments During
       the Year ....................................................    (27,055,878)      7,227,689
                                                                       ------------    ------------

     Net Gain (Loss) on Investments ................................   $(21,106,083)   $ 10,898,432
                                                                       ============    ============

</TABLE>



**   Represents operations through April 29, 1993.
 #   Commenced operations on April 30, 1993.
##   Commenced operations on May 3, 1994.


                See Notes to Financial Statements on page 31-32.


                                                                               8
<PAGE>   9


Item 6.    (continued)

     Changes in Equity for NML Variable  Annuity  Account C for each of the five
years ending December 31, follows:

<TABLE>
<CAPTION>
                                                                             1997             1996              1995     
                                                                         ------------    -------------     ------------- 
<S>                                                                     <C>              <C>              <C>          
From Investment Activities

     Net Investment Income ..........................................   $  25,187,188    $  15,255,745    $   5,614,012

     Net Realized Gain (Loss) on Investments ........................      18,686,284        8,855,390        9,884,364

     Net Change in Unrealized Appreciation (Depreciation) of
       Investments ..................................................      44,241,434       29,832,124       53,407,857
                                                                        -------------    -------------    -------------

                                                                     
           Increase in Equity Derived from Investment Activities ...       88,114,906       53,943,259       68,906,233
                                                                        -------------    -------------    -------------
From Equity Transactions

     Contract Owners' Net Payments ..................................      91,195,224       89,650,916       59,390,267

     Surrenders and Other (Net) .....................................     (57,974,180)     (34,747,640)      60,872,729
                                                                        -------------    -------------    -------------

                                                              
           Increase in Equity Derived from Equity Transactions.......      33,221,044       54,903,276       (1,482,462)
                                                                        -------------    -------------    -------------
Net Increase in Equity ..............................................     121,335,950      108,846,535       67,423,771

Equity, Beginning of Year ...........................................     426,652,573      317,806,038      250,382,267
                                                                        -------------    -------------    -------------

Equity, End of Year .................................................   $ 547,988,523    $ 426,652,573    $ 317,806,038
                                                                        =============    =============    =============


<CAPTION>
                                                                             1994               1993
                                                                        -------------     -------------
<S>                                                                     <C>              <C>          
From Investment Activities

     Net Investment Income ..........................................   $  22,052,561    $   9,323,846

     Net Realized Gain (Loss) on Investments ........................       5,949,795        3,670,743

     Net Change in Unrealized Appreciation (Depreciation) of
       Investments ..................................................     (27,055,878)       7,227,689
                                                                        -------------    -------------

                                                                  
           Increase in Equity Derived from Investment Activities ...          946,478       20,222,278
                                                                        -------------    -------------
From Equity Transactions

     Contract Owners' Net Payments ..................................      48,709,729       39,748,661

     Surrenders and Other (Net) .....................................     (26,720,946)     (22,334,176)
                                                                        -------------    -------------

              Increase in Equity Derived from Equity Transactions ...
                                                                           21,988,783       17,414,485
                                                                        -------------    -------------
Net Increase in Equity ..............................................      22,935,261       37,636,763

Equity, Beginning of Year ...........................................     227,447,006      189,810,243
                                                                        -------------    -------------

Equity, End of Year .................................................   $ 250,382,267    $ 227,447,006
                                                                        =============    =============
</TABLE>





                See Notes to Financial Statements on page 31-32.


                                                                               9
<PAGE>   10


Item 6.    (continued)
     Total Assets of NML Variable Annuity Account C for each of the five
following years at December 31, follows: 

<TABLE>
<CAPTION>
                                                                            1997           1996             1995    
                                                                        ------------   ------------    ------------ 
Assets
<S>                                                                   <C>             <C>             <C>         
    Investments at Market Value:

     Northwestern Mutual Series Fund, Inc. Aggressive Growth Stock
       Portfolio ....................................................   $111,586,520   $ 95,276,983   $ 57,421,016

     Northwestern Mutual Series Fund, Inc. International Equity
       Portfolio ....................................................     63,877,146     49,461,520     30,039,223

                                                                     
     Northwestern Mutual Series Fund, Inc. Growth Stock Portfolio ...     15,850,257      9,734,427      2,084,697

     Northwestern Mutual Series Fund, Inc. Growth and Income Stock
       Portfolio ....................................................     27,484,626     13,034,961      4,888,505

     Northwestern Mutual Series Fund, Inc. Index 500 Stock 
       Portfolio ....................................................    133,927,705     93,249,123     64,560,752

     Northwestern Mutual Series Fund, Inc. Balanced 
       Portfolio.....................................................    153,733,599    131,324,909    132,469,239

     Northwestern Mutual Series Fund, Inc. High Yield Bond 
       Portfolio.....................................................      6,568,438      2,983,258        736,774

     Northwestern Mutual Series Fund, Inc. Select Bond 
       Portfolio.....................................................     18,059,926     17,803,016     16,281,140

     Northwestern Mutual Series Fund, Inc. Money Market 
       Portfolio ....................................................     16,900,306     13,784,374      9,324,692

Due from NML Insurance Company ......................................        196,511      1,662,368        808,493

Due from Sale of Fund Shares ........................................      2,927,350         52,909             36
                                                                        ------------   ------------   ------------

                  Total Assets ......................................   $551,112,384   $428,367,848   $318,614,567
                                                                        ============   ============   ============


<CAPTION>

                                                                             1994         1993
                                                                        ------------   ------------
<S>                                                                     <C>            <C>         
Assets
    Investments at Market Value:

     Northwestern Mutual Series Fund, Inc. Aggressive Growth Stock
       Portfolio ....................................................   $ 33,266,862   $ 21,836,950

     Northwestern Mutual Series Fund, Inc. International Equity
       Portfolio ....................................................     24,647,586      3,183,126#

     Northwestern Mutual Series Fund, Inc. Growth Stock 
       Portfolio ....................................................        329,792##           NA

     Northwestern Mutual Series Fund, Inc. Growth and Income Stock
       Portfolio ....................................................      1,159,187##           NA

     Northwestern Mutual Series Fund, Inc. Index 500 Stock 
       Portfolio ....................................................     45,552,429     45,850,766

     Northwestern Mutual Series Fund, Inc. Balanced 
       Portfolio ....................................................    119,452,506    131,574,218

     Northwestern Mutual Series Fund, Inc. High Yield Bond 
       Portfolio ....................................................        201,656##           NA

     Northwestern Mutual Series Fund, Inc. Select Bond 
       Portfolio ....................................................     14,262,125     15,071,860

     Northwestern Mutual Series Fund, Inc. Money Market 
       Portfolio ....................................................     11,510,121      9,930,082

Due from NML Insurance Company ......................................        279,107         35,475

Due from Sale of Fund Shares ........................................         79,226        145,027
                                                                        ------------   ------------

                  Total Assets ......................................   $250,740,600   $227,627,504
                                                                        ============   ============
</TABLE>



 #   Commenced operations on April 30, 1993.
##   Commenced operations on May 3, 1994.

                See Notes to Financial Statements on page 31-32.

                                                                            
                             Item 7 is on page 11.


                                                                              10





  
<PAGE>   11

                 The Northwestern Mutual Life Insurance Company
                                   Form 10-K



Item 7. Management's Discussion and Analysis of Financial Condition and
        Results of Operations

          (a)   Liquidity

                The assets of the Northwestern Mutual Life Insurance Company
                Variable Annuity Account A and C are invested solely in shares
                of Northwestern Mutual Series Fund, Inc. Index 500 Stock
                Portfolio, Northwestern Mutual Series Fund, Inc. Aggressive
                Growth Stock Portfolio, Northwestern Mutual Series Fund, Inc.
                International Equity Portfolio, Northwestern Mutual Series
                Fund, Inc. Select Bond Portfolio, Northwestern Mutual Series
                Fund, Inc. Growth and Income Stock Portfolio, and Northwestern
                Mutual Series Fund, Inc. High Yield Bond Portfolio (the
                "Funds").  The Funds are open-end investment companies
                registered under the Investment Act of 1940.  In order to pay
                annuity benefits and expenses, the Accounts redeem shares in
                these Funds.  The Registrant's liquidity is not expected to
                change in a material way.

          (b)   Capital Resources

                All payments from contract owners of NML Variable Annuity
                Accounts A and C are invested in shares of the Funds.  The
                capital resources of NML Variable Annuity Accounts A and C are
                the equity in the respective Accounts.  This consists of
                payments from the contract owners, plus unrealized and realized
                appreciation on the investment of these payments, plus
                investment income received from the Funds, minus payment of
                annuity benefits and expenses.

          (c)   Results of Operations

                        NML Variable Annuity Account A

          Accumulation Unit Values
          Contracts Issued Prior to December 17, 1981:


<TABLE>
<CAPTION>
         Division               12/31/97   % of Change  12/31/96   % of Change  12/31/95   
         --------               ---------  -----------  ---------  -----------  ---------  
         <S>                    <C>        <C>          <C>        <C>          <C>        
         Agressive Growth                                                                  
         Stock................. $3.714008       13.02%  $3.286265       16.82%  $2.813200  
         International Equity..  1.871861       11.44    1.679665       20.11    1.398467  
         Growth Stock..........  2.027359       28.89    1.572985       20.00    1.310823  
         Growth and Income                                                                 
         Stock.................  1.994748       29.06    1.545596       19.07    1.298065  
         Index 500 Stock.......  3.289255       32.21    2.487952       21.83    2.042204  
         Balanced..............  6.248153       20.61    5.180408       12.60    4.600659  
         High Yield Bond.......  1.624115       14.99    1.412413       18.87    1.188188  
         Select Bond...........  7.263164        8.65    6.685035        2.54    6.519655  
         Money Market..........  2.529098        4.69    2.415898        4.49    2.311989  
</TABLE>



                                                                             11
<PAGE>   12

                 The Northwestern Mutual Life Insurance Company
                                   Form 10-K




Item 7.  (continued)

         Accumulation Unit Values
         Contracts Issued After December 16, 1981 and Prior to March 31, 1995:



<TABLE>
<CAPTION>
          Division                       12/31/97   % of Change  12/31/96   % of Change  12/31/95  
          --------                       ---------  -----------  ---------  -----------  --------- 
          <S>                            <C>        <C>          <C>        <C>          <C>       
          Aggressive Growth                                                                         
          Stock......................... $3.585281       12.45%  $3.188266       16.23%  $2.743106 
          International Equity..........  1.828649       10.89    1.649102       19.50    1.379966 
          Growth Stock..................  1.990509       28.24    1.552125       19.40    1.299976 
          Growth and Income                                                                        
          Stock.........................  1.958555       28.42    1.525144       18.47    1.287355 
          Index 500 Stock...............  3.175298       31.55    2.413788       21.21    1.991330 
          Balanced......................  5.767570       20.01    4.805896       12.04    4.289623 
          High Yield Bond...............  1.594619       14.42    1.393713       18.27    1.178371 
          Select Bond...................  6.703164        8.11    6.200523        2.02    6.077689 
          Money Market..................  2.334748        4.16    2.241420        3.97    2.155845 
</TABLE>

          Accumulation Unit Values
          Contracts Issued On or After March 31, 1995:
          Front Load Version


<TABLE>
<CAPTION>
          Division                      12/31/97   % of Change  12/31/96   % of Change  12/31/95
          --------                      ---------  -----------  ---------  -----------  ---------
          <S>                           <C>        <C>          <C>        <C>          <C>
          Aggressive  Growth             
          Stock........................ $1.735135       13.41%  $1.529999       17.22%  $1.305186
          International Equity.........  1.537080       11.83    1.374484       20.53    1.140398
          Growth Stock.................  1.882500       29.33    1.455537       20.42    1.208718
          Growth and Income       
          Stock........................  1.851666       29.51    1.429760       19.49    1.196596
          Index 500 Stock..............  2.025922       32.67    1.527085       22.25    1.249114
          Balanced.....................  1.615054       21.03    1.334426       13.00    1.180953
          High Yield Bond..............  1.530051       15.39    1.326020       19.29    1.111614
          Select Bond..................  1.266282        9.03    1.161454        2.90    1.128765
          Money Market.................  1.145720        5.05    1.090643        4.86    1.040089
</TABLE>



                                                                             12
<PAGE>   13

                 The Northwestern Mutual Life Insurance Company
                                   Form 10-K




Item 7.  (continued)

         Accumulation Unit Values
         Contracts Issued On or After March 31, 1995:
         Back Load Version



<TABLE>
<CAPTION>
          Division                12/31/97     % of Change     12/31/96    % of Change  12/31/95   
          --------              ------------  -------------  ------------  -----------  ---------  
          <S>                   <C>           <C>            <C>           <C>          <C>        
          Aggressive  Growth                                                                       
          Stock................ $   3.585281         12.45%  $   3.188266       16.23%  $2.743106  
          International Equity.     1.828649         10.89       1.649102       19.50    1.379966  
          Growth Stock.........     1.990509         28.24       1.552125       19.40    1.299976  
          Growth and Income                                                                        
          Stock................     1.958555         28.42       1.525144       18.47    1.287355  
          Index 500 Stock......     3.175298         31.55       2.413788       21.21    1.991330  
          Balanced.............     5.767570         20.01       4.805896       12.04    4.289623  
          High Yield Bond......     1.594619         14.42       1.393713       18.27    1.178371  
          Select Bond..........     6.703164          8.11       6.200523        2.02    6.077689  
          Money Market.........     2.334748          4.16       2.241420        3.97    2.155845  

                       Equity:                                                                     
                                  12/31/97      12/31/96       12/31/95                            
                                ------------  -------------  ------------                          
                                $648,394,089  $547,520,040   $469,821,427                          
</TABLE>

          The change in these amounts is largely derived from investment
          activities within the Account:  A $96,695,584 increase for the year
          ended December 31, 1995, a $65,736,696 increase for the year ended
          December 31, 1996, and a $105,703,026 increase for the year ended
          December 31, 1997.  Net contributions (surrenders) from contract
          owners amounted to $(13,795,319) for the year ended December 31,
          1995, $11,961,917 for the year ended December 31, 1996, and
          $(4,828,977) for the year ended December 31, 1997.



                         NML Variable Annuity Account
          Accumulation Unit Values
          Contracts Issued Prior to December 17, 1981 or between April 30, 1984
          and December 31, 1991:


<TABLE>
<CAPTION>
          Division               12/31/97   % of Change   12/31/96   % of Change   12/31/95   
          --------              ----------  -----------  ----------  -----------  ----------  
          <S>                   <C>         <C>          <C>         <C>          <C>         
          Aggressive Growth                                                                   
          Stock................ $37.054456       13.86%  $32.542621       17.70%  $27.648691  
          International Equity.   1.938399       12.28     1.726413       21.01     1.426613  
          Growth Stock.........  20.837268       29.85    16.046821       20.91    13.271899  
          Growth and Income                                                                   
          Stock................  20.502206       30.03    15.767435       19.97    13.142782  
          Index 500 Stock......  36.141676       33.20    27.133645       22.75    22.104982  
          Balanced.............  71.490869       21.52    58.832423       13.45    51.855817  
          High Yield Bond......  16.692972       15.85    14.408967       19.77    12.030416  
          Select Bond..........  83.938645        9.46    76.681608        3.31    74.222515  
          Money Market.........  27.434762        5.47    26.011476        5.29    24.705630  
</TABLE>




                                                                            13
<PAGE>   14

                 The Northwestern Mutual Life Insurance Company
                                   Form 10-K




Item 7.  (continued)

         Accumulation Unit Values
         Contracts Issued After December 16, 1981 or Prior to May 1, 1984:



<TABLE>
<CAPTION>
          Division                   12/31/97   % of Change   12/31/96   % of Change   12/31/95    
          --------                  ----------  -----------  ----------  -----------  ----------   
          <S>                       <C>         <C>          <C>         <C>          <C>          
          Aggressive Growth                                                                    
          Stock...................  $35.791674       13.30%  $31.591115       17.11%  $26.975930   
          International Equity....    1.893664       11.72     1.695019       20.41     1.407741   
          Growth Stock............   20.458788       29.21    15.834243       20.30    13.162242   
          Growth and Income                                                                        
          Stock...................   20.129770       29.38    15.558532       19.37    13.034162   
          Index 500 Stock.........   34.906216       32.54    26.337300       22.13    21.564611   
          Balanced................   66.012286       20.91    54.595947       12.88    48.364840   
          High Yield Bond.........   16.389706       15.27    14.218083       19.17    11.931003   
          Select Bond.............   77.468103        8.92    71.125132        2.79    69.192181   
          Money Market............   25.362364        4.95    24.167111        4.76    23.069838   
</TABLE>

          Accumulation Unit Values
          Contracts Issued After December 31, 1991 - Front Load Version:


<TABLE>
<CAPTION>
          Division                      12/31/97   % of Change  12/31/96   % of Change  12/31/95   
          --------                      ---------  -----------  ---------  -----------  ---------  
          <S>                            <C>        <C>          <C>        <C>          <C>        
          Aggressive Growth                                                                 
          Stock........................  $2.350498       13.13%  $2.077739       16.93%  $1.776871  
          International Equity.........   1.880500       11.55    1.685759       20.23    1.402156  
          Growth Stock.................   2.034708       29.01    1.577134       20.12    1.312966  
          Growth and Income                                                                         
          Stock........................   2.001981       29.19    1.549666       19.19    1.300190  
          Index 500 Stock..............   2.563560       32.34    1.937139       21.95    1.588496  
          Balanced.....................   1.931409       20.73    1.599774       12.71    1.419325  
          High Yield Bond..............   1.630023       15.10    1.416152       18.99    1.190149  
          Select Bond..................   1.490112        8.75    1.370157        2.64    1.334934  
          Money Market.................   1.249188        4.79    1.192105        4.60    1.139693  
</TABLE>


                                                                            14

<PAGE>   15

                 The Northwestern Mutual Life Insurance Company
                                   Form 10-K




Item 7.  (continued)

              Accumulation Unit Values
              Contracts Issued After December 31, 1991 - Simplified Load
              Version: 



<TABLE>
<CAPTION>
              Division                   12/31/97   % of Change  12/31/96   % of Change  12/31/95   
              --------                   ---------  -----------  ---------  -----------  ---------  
              <S>                         <C>        <C>          <C>        <C>          <C>        
              Aggressive Growth                                                                 
              Stock....................   $3.598431       12.45%  $3.199964       16.23%  $2.753170  
              International Equity.....   1.828649       10.89    1.649102       19.50    1.379966  
              Growth Stock.............   1.990509       28.24    1.552125       19.40    1.299976  
              Growth and Income                                                                     
              Stock....................   1.958555       28.42    1.525144       18.47    1.287355  
              Index 500 Stock..........   3.240055       31.55    2.463008       21.22    2.031929  
              Balanced.................   5.796067       20.01    4.829655       12.04    4.310821  
              High Yield Bond..........   1.594619       14.42    1.393713       18.27    1.178371  
              Select Bond..............   6.768475        8.11    6.260939        2.02    6.136911  
              Money Market.............   2.339812        4.16    2.246287        3.97    2.160533  

                Equity:
                                        12/31/97      12/31/96      12/31/95           
                                      ------------  ------------  ------------         
                                      <C>           <C>           <C>                  
                                      $547,988,523  $426,652,573  $317,806,038         

</TABLE>

          These changes are largely derived from investment activities within
          the Account: A $68,906,233 increase for the year ended December 31,
          1995, a $53,943,259 increase for the year ended December 31, 1996,
          and a $88,114,906 increase for the year ended December 31, 1997.  Net
          contributions (surrenders) from contract owners amounted to
          $(1,482,462) for the year ended December 31, 1995, $54,903,276 for
          the year ended December 31, 1996, and $33,221,044 for the year ended
          December 31, 1997.



                             Item 8 is on page 16.

                                                                           15

<PAGE>   16

                 The Northwestern Mutual Life Insurance Company
                                   Form 10-K



Item 8. Financial Statements and Supplementary Data

                         NML VARIABLE ANNUITY ACCOUNT A
                      STATEMENT OF ASSETS AND LIABILITIES


<TABLE>
<CAPTION>
                                                                December 31
                                                      --------------------------------
Assets                                                     1997             1996
                                                      ---------------  ---------------
<S>                                                   <C>              <C>
 Investments at market value:

  Northwestern Mutual Series Fund, Inc.

   Aggressive Growth Stock
    1997:  26,799,138 shares (cost $63,803,191).....  $    89,428,723  $    78,087,972
    1996:  24,829,244 shares (cost $54,025,343).....  

   International Equity
    1997:  29,691,199 shares (cost $40,304,940).....       50,148,435       41,497,787
    1996:  26,635,293 shares (cost $34,100,468).....       

   Growth Stock
    1997:  9,536,195 shares (cost $13,891,054)......       17,260,514        9,523,179
    1996:  6,504,903 shares (cost $8,193,212).......       

   Growth and Income Stock
    1997:  17,712,678 shares (cost $23,485,676).....       23,575,574       13,199,558
    1996:  10,014,839 shares (cost $11,804,187).....       

   Index 500 Stock
    1997:  42,035,107 shares (cost $62,642,616).....      111,140,823       80,917,025
    1996:  39,375,681 shares (cost $51,893,158).....      

   Balanced
    1997:  152,059,221 shares (cost $210,403,734)...      302,749,909      270,745,111
    1996:  157,593,196 shares (cost $210,643,607)...      

   High Yield Bond
    1997:  8,225,197 shares (cost $9,217,130).......        8,743,385        4,907,490
    1996:  4,465,414 shares (cost $4,847,740).......        

   Select Bond
    1997:  20,089,875 shares (cost $23,555,171).....       25,252,973       26,648,961
    1996:  21,772,027 shares (cost $25,386,654).....       

   Money Market
    1997:  21,586,115 shares (cost $21,586,115).....       21,586,115       23,380,205
    1996:  23,380,205 shares (cost $23,380,205).....
                                                      ---------------  ---------------
                                                          649,886,451      548,907,288

 Due from Sales of Fund Shares......................        1,555,441          387,086
 Due from Northwestern Mutual Life Insurance Company          322,747          123,152
                                                      ---------------  ---------------
    Total Assets....................................  $   651,764,639  $   549,417,526
                                                      ===============  ===============

Liabilities
 Due to Participants................................  $     1,492,363  $     1,387,248
 Due to Northwestern Mutual Life Insurance Company..        1,555,441          387,086
 Due from Purchase of Fund Shares...................          322,747          123,152
                                                      ---------------  ---------------
    Total Liabilities...............................  $     3,370,551  $     1,897,484
                                                      ===============  ===============
</TABLE>

    The Accompanying Notes are an Integral Part of the Financial Statements.

                                                                       16

<PAGE>   17

                 The Northwestern Mutual Life Insurance Company
                                   Form 10-K



Item 8. (continued)

                         NML VARIABLE ANNUITY ACCOUNT A
                      STATEMENT OF ASSETS AND LIABILITIES


<TABLE>
<CAPTION>
                                                                      December 31              
                                                           ----------------------------------  
Equity                                                           1997              1996        
                                                           ----------------  ----------------  
<S>                                                        <C>               <C>               
 Contracts Issued Prior to December 17, 1981:                                                  
  Aggressive Growth Stock Division                                                             
   1997:  640,838 Accumulation Units @ 3.714008..........  $      2,380,076                    
   1996:  890,850 Accumulation Units @ 3.286265..........                    $      2,927,568  
   Annuity Reserves......................................            71,827            75,244  
                                                           ----------------  ----------------  
                                                                  2,451,903         3,002,812  
                                                           ----------------  ----------------  
  International Equity Division                                                                
   1997:  1,297,660 Accumulation Units @ 1.871861........         2,429,039                    
   1996:  1,332,812 Accumulation Units @ 1.679665........                           2,238,678  
   Annuity Reserves......................................           150,892           147,829  
                                                           ----------------  ----------------  
                                                                  2,579,931         2,386,507  
                                                           ----------------  ----------------  
  Growth Stock Division                                                                        
   1997:  327,731 Accumulation Units @ 2.027359..........           664,427                    
   1996:  118,168 Accumulation Units @ 1.572985..........                             185,861  
   Annuity Reserves......................................                 0             9,807  
                                                           ----------------  ----------------  
                                                                    664,427           195,668  
                                                           ----------------  ----------------  
  Growth and Income Stock Division                                                             
   1997:  348,188 Accumulation Units @ 1.994748..........           694,546                    
   1996:  69,566 Accumulation Units @ 1.545596...........                             107,521  
   Annuity Reserves......................................                 0           180,931  
                                                           ----------------  ----------------  
                                                                    694,546           288,452  
                                                           ----------------  ----------------  
  Index 500 Stock Division                                                                     
   1997:  8,175,537 Accumulation Units @ 3.289255........        26,891,427                    
   1996:  9,600,286 Accumulation Units @ 2.487952........                          23,885,052  
   Annuity Reserves......................................         1,305,930         1,300,177  
                                                           ----------------  ----------------  
                                                                 28,197,357        25,185,229  
                                                           ----------------  ----------------  
  Balanced Division                                                                            
   1997:  3,845,538 Accumulation Units @ 6.248153........        24,027,509                    
   1996:  4,743,812 Accumulation Units @ 5.180408........                          24,574,880  
   Annuity Reserves......................................         1,640,281         1,454,827  
                                                           ----------------  ----------------  
                                                                 25,667,790        26,029,707  
                                                           ----------------  ----------------  
  High Yield Bond Division                                                                     
   1997:  600,752 Accumulation Units @ 1.624115..........           975,690                    
   1996:  428,588 Accumulation Units @ 1.412413..........                             605,343  
   Annuity Reserves......................................                 0             7,644  
                                                           ----------------  ----------------  
                                                                    975,690           612,987  
                                                           ----------------  ----------------  
  Select Bond Division                                                                         
   1997:  1,012,083 Accumulation Units @ 7.263164........         7,350,925                    
   1996:  1,215,131 Accumulation Units @ 6.685035........                           8,123,192  
   Annuity Reserves......................................           273,840            75,632  
                                                           ----------------  ----------------  
                                                                  7,624,765         8,198,824  
                                                           ----------------  ----------------  
  Money Market Division                                                                        
   1997:  893,452 Accumulation Units @ 2.529098..........         2,259,628                    
   1996:  1,103,625 Accumulation Units @ 2.415898........                           2,666,245  
   Annuity Reserves......................................            58,694            60,981  
                                                           ----------------  ----------------  
                                                                  2,318,322         2,727,226  
                                                           ----------------  ----------------  
</TABLE>

    The Accompanying Notes are an Integral Part of the Financial Statements.

                                                                        17

<PAGE>   18

                 The Northwestern Mutual Life Insurance Company
                                   Form 10-K



Item 8. (continued)

                         NML VARIABLE ANNUITY ACCOUNT A
                      STATEMENT OF ASSETS AND LIABILITIES


<TABLE>
<CAPTION>
                                                                           December 31              
                                                                ----------------------------------  
Equity (cont'd.)                                                      1997              1996        
                                                                ----------------  ----------------  
<S>                                                             <C>               <C>               
 Contracts Issued After December 16, 1981 and                                                       
Prior to March 31, 1995:                                                                            
  Aggressive Growth Stock Division                                                                  
   1997:  20,861,309 Accumulation Units @ 3.585281..........    $     74,793,655                    
   1996:  21,479,837 Accumulation Units @ 3.188266..........                      $     68,483,433  
   Annuity Reserves.........................................             137,989           191,587  
                                                                ----------------  ----------------  
                                                                      74,931,644        68,675,020  
                                                                ----------------  ----------------  
  International Equity Division                                                                     
   1997:  22,910,908 Accumulation Units @ 1.828649..........          41,896,009                    
   1996:  22,132,206 Accumulation Units @ 1.649102..........                            36,498,266  
   Annuity Reserves.........................................             174,073           100,731  
                                                                ----------------  ----------------  
                                                                      42,070,082        36,598,997  
                                                                ----------------  ----------------  
  Growth Stock Division                                                                             
   1997:  6,045,075 Accumulation Units @ 1.990509...........          12,032,777                    
   1996:  4,845,965 Accumulation Units @ 1.552125...........                             7,521,543  
   Annuity Reserves.........................................              11,803                    
                                                                ----------------  ----------------  
                                                                      12,044,580         7,521,543  
                                                                ----------------  ----------------  
  Growth and Income Stock Division                                                                  
   1997:  8,963,724 Accumulation Units @ 1.958555...........          17,555,947                    
   1996:  7,054,484 Accumulation Units @ 1.525144...........                            10,759,104  
   Annuity Reserves:........................................             332,207                    
                                                                ----------------  ----------------  
                                                                      17,888,154        10,759,104  
                                                                ----------------  ----------------  
  Index 500 Stock Division                                                                          
   1997:  21,531,879 Accumulation Units @ 3.175298..........          68,370,132                    
   1996:  20,092,060 Accumulation Units @ 2.413788..........                            48,497,973  
   Annuity Reserves.........................................           2,462,112         1,673,310  
                                                                ----------------  ----------------  
                                                                      70,832,244        50,171,283  
                                                                ----------------  ----------------  
  Balanced Division                                                                                 
   1997:  44,638,127 Accumulation Units @ 5.767570..........         257,453,521                    
   1996:  48,457,793 Accumulation Units @ 4.805896..........                           232,883,113  
   Annuity Reserves.........................................           3,937,936         3,048,888  
                                                                ----------------  ----------------  
                                                                     261,391,457       235,932,001  
                                                                ----------------  ----------------  
  High Yield Bond Division                                                                          
   1997:  3,770,055 Accumulation Units @ 1.594619...........           6,011,801                    
   1996:  2,456,295 Accumulation Units @ 1.393713...........                             3,423,371  
   Annuity Reserves.........................................              67,256                    
                                                                ----------------  ----------------  
                                                                       6,079,057         3,423,371  
                                                                ----------------  ----------------  
  Select Bond Division                                                                              
   1997:  2,252,704 Accumulation Units @ 6.703164...........          15,100,242                    
   1996:  2,691,481 Accumulation Units @ 6.200523...........                            16,688,589  
   Annuity Reserves.........................................             591,284           580,678  
                                                                ----------------  ----------------  
                                                                      15,691,526        17,269,267  
                                                                ----------------  ----------------  
  Money Market Division                                                                             
   1997:  6,270,333 Accumulation Units @ 2.334748...........          14,639,648                    
   1996:  7,029,739 Accumulation Units @ 2.241420...........                            15,756,598  
   Annuity Reserves.........................................             454,275           368,369  
                                                                ----------------  ----------------  
                                                                      15,093,923        16,124,967  
                                                                ----------------  ----------------  
</TABLE>

    The Accompanying Notes are an Integral Part of the Financial Statements.


                                                                         18
<PAGE>   19

                 The Northwestern Mutual Life Insurance Company
                                   Form 10-K



Item 8. (continued)

                         NML VARIABLE ANNUITY ACCOUNT A
                      STATEMENT OF ASSETS AND LIABILITIES


<TABLE>
<CAPTION>
                                                                             December 31
                                                                   --------------------------------
Equity (cont'd.)                                                        1997             1996
                                                                   ---------------  ---------------
<S>                                                                <C>              <C>
 Contracts Issued On or After March 31, 1995 - Back Load Version:
  Aggressive Growth Stock Division
   1997:  2,926,218 Accumulation Units @ 3.585281................  $    10,491,351
   1996:  1,734,023 Accumulation Units @ 3.188266................                   $     5,528,526
   Annuity Reserves..............................................           27,274
                                                                   ---------------  ---------------
                                                                        10,518,625        5,528,526
                                                                   ---------------  ---------------
  International Equity Division
   1997:  2,488,184 Accumulation Units @ 1.828649................        4,550,016
   1996:  1,281,128 Accumulation Units @ 1.649102................                         2,112,711
   Annuity Reserves..............................................                0
                                                                   ---------------  ---------------
                                                                         4,550,016        2,112,711
                                                                   ---------------  ---------------
  Growth Stock Division
   1997:  1,870,296 Accumulation Units @ 1.990509................        3,722,840
   1996:  922,390 Accumulation Units @ 1.552125..................                         1,431,665
   Annuity Reserves..............................................           26,907
                                                                   ---------------  ---------------
                                                                         3,749,747        1,431,665
                                                                   ---------------  ---------------
  Growth and Income Stock Division
   1997:  1,940,827 Accumulation Units @ 1.958555................        3,801,216
   1996:  1,215,721 Accumulation Units @ 1.525144................                         1,854,150
   Annuity Reserves..............................................           26,336
                                                                   ---------------  ---------------
                                                                         3,827,552        1,854,150
                                                                   ---------------  ---------------
  Index 500 Stock Division
   1997:  3,279,176 Accumulation Units @ 3.175298................       10,412,362
   1996:  1,970,961 Accumulation Units @ 2.413788................                         4,757,482
   Annuity Reserves..............................................                0
                                                                   ---------------  ---------------
                                                                        10,412,362        4,757,482
                                                                   ---------------  ---------------
  Balanced Division
   1997:  2,109,606 Accumulation Units @ 5.767570................       12,167,299
   1996:  1,347,427 Accumulation Units @ 4.805896................                         6,475,593
   Annuity Reserves..............................................          219,112
                                                                   ---------------  ---------------
                                                                        12,386,411        6,475,593
                                                                   ---------------  ---------------
  High Yield Bond Division
   1997:  967,188 Accumulation Units @ 1.594619..................        1,542,185
   1996:  572,121 Accumulation Units @ 1.393713..................                           797,373
   Annuity Reserves..............................................                0
                                                                   ---------------  ---------------
                                                                         1,542,185          797,373
                                                                   ---------------  ---------------
  Select Bond Division
   1997:  271,027 Accumulation Units @ 6.703164..................        1,816,737
   1996:  182,907 Accumulation Units @ 6.200523..................                         1,134,116
   Annuity Reserves..............................................                0
                                                                   ---------------  ---------------
                                                                         1,816,737        1,134,116
                                                                   ---------------  ---------------
  Money Market Division
   1997:  1,081,227 Accumulation Units @ 2.334748................        2,524,393
   1996:  1,123,081 Accumulation Units @ 2.241420................                         2,517,297
   Annuity Reserves..............................................                0
                                                                   ---------------  ---------------
                                                                         2,524,393        2,517,297
                                                                   ---------------  ---------------
</TABLE>

    The Accompanying Notes are an Integral Part of the Financial Statements.


                                                                         19
<PAGE>   20

                 The Northwestern Mutual Life Insurance Company
                                   Form 10-K



Item 8. (continued)

                         NML VARIABLE ANNUITY ACCOUNT A
                      STATEMENT OF ASSETS AND LIABILITIES


<TABLE>
<CAPTION>
                                                                              December 31
                                                                    --------------------------------
Equity (cont'd.)                                                         1997             1996
                                                                    ---------------  ---------------
<S>                                                                 <C>              <C>
 Contracts Issued On or After March 31, 1995 - Front Load Version:
  Aggressive Growth Stock Division
   1997:  832,513 Accumulation Units @ 1.735135...................  $     1,444,522
   1996:  568,732 Accumulation Units @ 1.529999...................                   $       870,160
   Annuity Reserves...............................................           55,374
                                                                    ---------------  ---------------
                                                                          1,499,896          870,160
                                                                    ---------------  ---------------
  International Equity Division
   1997:  575,775 Accumulation Units @ 1.537080...................          885,012
   1996:  286,469 Accumulation Units @ 1.374484...................                           393,747
   Annuity Reserves...............................................           24,148
                                                                    ---------------  ---------------
                                                                            909,160          393,747
                                                                    ---------------  ---------------
  Growth Stock Division
   1997:  422,029 Accumulation Units @ 1.882500...................          794,469
   1996:  257,158 Accumulation Units @ 1.455537...................                           374,303
   Annuity Reserves...............................................                0
                                                                    ---------------  ---------------
                                                                            794,469          374,303
                                                                    ---------------  ---------------
  Growth and Income Stock Division
   1997:  540,977 Accumulation Units @ 1.851666...................        1,001,708
   1996:  208,323 Accumulation Units @ 1.429760...................                           297,852
   Annuity Reserves...............................................          133,668
                                                                    ---------------  ---------------
                                                                          1,135,376          297,852
                                                                    ---------------  ---------------
  Index 500 Stock Division
   1997:  690,248 Accumulation Units @ 2.025922...................        1,398,389
   1996:  454,096 Accumulation Units @ 1.527085...................                           693,444
   Annuity Reserves...............................................           54,108
                                                                    ---------------  ---------------
                                                                          1,452,497          693,444
                                                                    ---------------  ---------------
  Balanced Division
   1997:  1,296,330 Accumulation Units @ 1.615054.................        2,093,642
   1996:  786,271 Accumulation Units @ 1.334426...................                         1,049,220
   Annuity Reserves...............................................           95,364
                                                                    ---------------  ---------------
                                                                          2,189,006        1,049,220
                                                                    ---------------  ---------------
  High Yield Bond Division
   1997:  95,718 Accumulation Units @ 1.530051....................          146,453
   1996:  55,625 Accumulation Units @ 1.326020....................                            73,760
   Annuity Reserves...............................................                0
                                                                    ---------------  ---------------
                                                                            146,453           73,760
                                                                    ---------------  ---------------
  Select Bond Division
   1997:  72,941 Accumulation Units @ 1.266282....................           92,364
   1996:  38,713 Accumulation Units @ 1.161454....................                            44,963
   Annuity Reserves...............................................                0
                                                                    ---------------  ---------------
                                                                             92,364           44,963
                                                                    ---------------  ---------------
  Money Market Division
   1997:  1,439,686 Accumulation Units @ 1.145720.................        1,649,477
   1996:  1,843,605 Accumulation Units @ 1.090643.................                         2,010,715
   Annuity Reserves...............................................                0
                                                                    ---------------  ---------------
                                                                          1,649,477        2,010,715
                                                                    ---------------  ---------------
         Total Equity.............................................  $   648,394,124  $   547,520,042
                                                                    ---------------  ---------------
         Total Liabilities and Equity.............................  $   651,764,675  $   549,417,526
                                                                    ===============  ===============
</TABLE>

    The Accompanying Notes are an Integral Part of the Financial Statements.



                                                                         20
<PAGE>   21

                 The Northwestern Mutual Life Insurance Company
                                   Form 10-K



Item 8. (continued)

                         NML VARIABLE ANNUITY ACCOUNT A
             COMBINED STATEMENT OF OPERATIONS AND CHANGES IN EQUITY
                        For the Years Ended December 31



<TABLE>
<CAPTION>
                                                                    1997           1996           1995
                                                                -------------  -------------  -------------
<S>                                                             <C>            <C>            <C>
Investment Income
 Dividend Income..............................................  $ 33,252,128   $ 24,500,542   $ 11,709,964
 Annuity Rate and Expense Guarantees..........................     7,048,888      5,783,739      5,072,064
                                                                ------------   ------------   ------------
 Net Investment Income........................................    26,203,240     18,716,803      6,637,900
                                                                ------------   ------------   ------------
Realized and Unrealized Gain on Investments
 Net Unrealized Gain on Investments...........................    23,135,675     13,967,988     13,141,169
 Unrealized Appreciation (Depreciation) During the Year.......    56,364,111     33,051,905     76,916,515
                                                                ------------   ------------   ------------
 Net Gain (Loss) on Investments...............................    79,499,786     47,019,893     90,057,684
                                                                ------------   ------------   ------------
Increase (Decrease) in Equity Derived from Investment Activity   105,703,026     65,736,696     96,695,584
                                                                ------------   ------------   ------------
Equity Transactions
 Contract Owners' Net Payments................................    61,964,558     65,169,358     49,124,853
 Annuity Payments.............................................    (1,046,956)      (830,996)      (610,983)
 Surrenders and Other (Net)...................................   (65,746,579)   (52,376,445)   (62,309,189)
                                                                ------------   ------------   ------------
Increase (Decrease) in Equity Derived from Equity Transactions    (4,828,977)    11,961,917    (13,795,319)
                                                                ------------   ------------   ------------
Net Increase in Equity........................................   100,874,049     77,698,613     82,900,265
Equity, Beginning of Year.....................................   547,520,040    469,821,427    386,921,162
                                                                ------------   ------------   ------------
Equity, End of Year...........................................  $648,394,089   $547,520,040   $469,821,427
                                                                ============   ============   ============
</TABLE>

    The Accompanying Notes are an Integral Part of the Financial Statements.



<PAGE>   22

                 The Northwestern Mutual Life Insurance Company
                                   Form 10-K



Item 8. (continued)

                         NML VARIABLE ANNUITY ACCOUNT A
                         NOTES TO FINANCIAL STATEMENTS

Note 1--NML Variable Annuity Account A (the "Account") is a segregated asset
account of The Northwestern Mutual Life Insurance Company ("Northwestern Mutual
Life") used to fund variable annuity contracts ("contracts") for HR-10 and
corporate pension and profit-sharing plans which qualify for special tax
treatment under the Internal Revenue Code.  Beginning March 31, 1995, two
versions of the contract are offered:  Front Load contracts with a sales charge
up to 4% of purchase payments and Back Load contracts with a withdrawal charge
of 0-8%.

Note 2--The preparation of the financial statements in conformity with
generally accepted accounting principles requires management to make estimates
and assumptions that affect the reported amounts of assets and liabilities and
disclosure of contingent assets and liabilities at the date of the financial
statements and the reported amounts of revenues and expenses during the
reporting period.  Actual results could differ from those estimates.  Principal
accounting policies are summarized below.

Note 3--All assets of each Division of the Account are invested in shares of
the corresponding Portfolio of Northwestern Mutual Series Fund, Inc. (the
"Fund").   The shares are valued at the Fund's offering and redemption price
per share.

On May 3, 1994, five new portfolios commenced operations in the Fund:
Aggressive Growth Stock Portfolio, International Equity Portfolio, Growth Stock
Portfolio, Growth and Income Stock Portfolio and High Yield Bond Portfolio.
Additionally, on May 3, 1994, the assets of Northwestern Mutual Life's Variable
Annuity funds were merged into the respective portfolio of the Fund in a
tax-free exchange of shares.

The Fund is an open-end investment company registered under the Investment
Company Act of 1940.

Note 4--Annuity reserves are based on published annuity tables with age
adjustment and benefit payments which reflect actual investment experience.
For variable payment plans issued prior to January 1, 1974, annuity reserves
are based on the 1955 American Annuity Table with assumed interest rates of 3%,
3 1/2% or 5%.  For variable payment plans issued on or after January 1, 1974
and before January 1, 1985, annuity reserves are based on the 1971 Individual
Annuity Table with assumed interest rates of 3 1/2% or 5%.  For variable
payment plans issued on or after January 1, 1985, annuity reserves are based on
the 1983 Table with assumed interest rates of 3 1/2% or 5%.

Note 5--Dividend income from the Fund is recorded on the record date of the
dividends.  Transactions in Fund shares are accounted for on the trade date.
The basis for determining cost on sale of Fund shares is identified cost.
Purchases and sales of Fund shares for the years ended December 31 by each
Division are shown below:


<TABLE>
<CAPTION>
Purchases                           1997          1996          1995
- ---------                       ------------  ------------  ------------
<S>                             <C>           <C>           <C>
Aggressive Growth Division       $13,774,024   $17,797,661   $10,658,292
International Equity Division      9,401,229     8,274,087     4,305,567
Growth Stock Division              6,679,256     4,830,460     2,702,664
Growth & Income Stock Division    13,074,930     5,756,071     4,147,264
Index 500 Stock Division          14,059,126    11,279,772     7,998,931
Balanced Division                 21,076,301    20,896,761    14,258,034
High Yield Bond Division           5,687,823     3,296,028     1,411,373
Select Bond Division               4,506,469     5,463,472     3,837,930
Money Market Division             13,132,202    13,328,217    14,421,123

Sales
- -----
Aggressive Growth Division       $ 8,367,827   $ 4,234,497   $ 5,672,013
International Equity Division      4,431,627     3,828,530     5,324,662
Growth Stock Division              1,576,559       508,512       427,690
Growth & Income Stock Division     2,076,927     1,277,020       576,160
Index 500 Stock Division           8,104,812     5,728,800     5,165,148
Balanced Division                 32,274,893    26,932,275    36,790,058
High Yield Bond Division           1,516,721       568,230       673,375
Select Bond Division               6,636,325     4,528,222     3,928,823
Money Market Division             14,926,292    11,504,938    12,987,931
</TABLE>


                                                                         22

<PAGE>   23

                 The Northwestern Mutual Life Insurance Company
                                   Form 10-K



Item 8. (continued)

                         NML VARIABLE ANNUITY ACCOUNT A
                         NOTES TO FINANCIAL STATEMENTS

Note 6--On April 30, 1993, Northwestern Mutual Capital Appreciation Stock Fund
was merged into the Northwestern Mutual Index 500 Stock Fund in a tax-free
exchange of fund shares.  21,689,286 shares of Northwestern Mutual Capital
Appreciation Stock Fund, Inc. were exchanged for 22,749,651 shares of
Northwestern Mutual Index 500 Stock Fund, Inc.  The shares exchanged were
valued at $30,719,638 for each Division.

Note 7--A deduction for annuity rate and expense guarantees is determined daily
and paid to Northwestern Mutual Life as compensation for assuming the risk that
annuity payments will continue for longer periods than anticipated because the
annuitants as a group live longer than expected, and the risk that the charges
made by Northwestern Mutual Life may be insufficient to cover the actual costs
incurred in connection with the contracts.

For contracts issued on or after March 31, 1995, for the Front Load version and
the Back Load version, the deduction for annuity rate and expense guarantees is
determined daily at annual rates of 4/10 of 1% and a1 1/4%, respectively, of
the net assets of each Division attributable to these contracts and is paid to
Northwestern Mutual Life.  For these contracts, the rates may be increased or
decreased by the Board of Trustees of Northwestern Mutual Life not to exceed
3/4 of 1% and 1 1/2%, respectively.

For contracts issued after December 16, 1981 and prior to March 31, 1995, the
deduction is at an annual rate of 1 1/4% of the net assets of each Division
attributable to these contracts.  For these contracts, the rate may be
increased or decreased by the Board of Trustees of Northwestern Mutual Life not
to exceed a 1 1/2% annual rate.

For contracts issued prior to December 17, 1981, the deduction is at an annual
rate of  3/4 of 1% of the net assets of each Division attributable to these
contracts.  For these contracts, the rate may be increased or decreased by the
Board of Trustees of Northwestern Mutual Life not to exceed a 1% annual rate.

Since 1995, Northwestern Mutual Life has paid a dividend to certain contracts.
The dividend is reinvested in the Account and has been reflected as a Contract
Owners' Net Payment in the accompanying financial statements.

Note 8--Northwestern Mutual Life is taxed as a "life insurance company" under
the Internal Revenue Code and the operations of the Account form a part of and
are taxed with those of Northwestern Mutual Life.  Under current law, no
federal income taxes are payable with respect to the Account.  Accordingly, no
provision for any such liability has been made.





                                                                        23


<PAGE>   24

                 The Northwestern Mutual Life Insurance Company
                                   Form 10-K



Item 8. (continued)

                         NML VARIABLE ANNUITY ACCOUNT C
                      STATEMENT OF ASSETS AND LIABILITIES


<TABLE>
<CAPTION>
                                                                December 31
                                                      --------------------------------
Assets                                                     1997             1996
                                                      --------------  ----------------
<S>                                                   <C>             <C>
 Investments at market value:
  Northwestern Mutual Series Fund, Inc.
   Aggressive Growth Stock
    1997:  33,439,173 shares (cost $85,858,851).....    $111,586,520      $ 95,276,983
    1996:  30,294,748 shares (cost $70,855,533).....    

   International Equity
    1997:  37,819,506 shares (cost $52,786,634).....      63,877,146        49,461,520
    1996:  31,746,803 shares (cost $41,642,844).....      

   Growth Stock
    1997:  8,757,048 shares (cost $13,278,855)......      15,850,257                  
    1996:  6,649,199 shares (cost $9,029,280).......                         9,734,427

   Growth and Income Stock
    1997:  20,649,607 shares (cost $28,811,270).....      27,484,626        13,034,961
    1996:  9,889,955 shares (cost $12,379,951)......      

   Index 500 Stock
    1997:  50,653,443 shares (cost $81,303,357).....     133,927,705                  
    1996:  45,376,702 shares (cost $63,645,634).....                        93,249,123

   Balanced
    1997:  77,214,264 shares (cost $114,230,115)....     153,733,599                  
    1996:  76,440,576 shares (cost $108,531,164)....                       131,324,909

   High Yield Bond
    1997:  6,179,152 shares (cost $6,940,417).......       6,568,438                  
    1996:  2,714,521 shares (cost $2,978,850).......                         2,983,258

   Select Bond
    1997:  14,367,483 shares (cost $16,785,623).....      18,059,926                  
    1996:  14,544,948 shares (cost $16,953,280).....                        17,803,016

   Money Market
    1997:  16,900,306 shares (cost $16,900,306).....      16,900,306        13,784,374
    1996:  13,784,374 shares (cost $13,784,374).....
                                                      --------------  ----------------
                                                         547,988,523       426,652,571

 Due from Sales of Fund Shares......................       2,927,350            52,909
 Due from Northwestern Mutual Life Insurance Company         196,511         1,662,368
                                                      --------------  ----------------
    Total Assets....................................  $  551,112,384  $    428,367,848
                                                      ==============  ================
Liabilities
 Due to Northwestern Mutual Life Insurance Company .  $    2,927,350  $         52,909
 Due from Purchase of Fund Shares...................         196,511         1,662,368
                                                      --------------  ----------------
    Total Liabilities...............................  $    3,123,861  $      1,715,277
                                                      ==============  ================
</TABLE>

    The Accompanying Notes are an Integral Part of the Financial Statements.


                                                                        24
<PAGE>   25

                 The Northwestern Mutual Life Insurance Company
                                   Form 10-K



Item 8. (continued)

                         NML VARIABLE ANNUITY ACCOUNT C
                      STATEMENT OF ASSETS AND LIABILITIES



<TABLE>
<CAPTION>
                                                                       December 31
                                                               ----------------------------
Equity                                                             1997           1996
                                                               -------------  -------------
<S>                                                            <C>            <C>              
 Contracts Issued Before December 17, 1981 or                                                  
  Between April 30, 1984 and December 31, 1991:                                                
                                                                                               
  Aggressive Growth Stock Division                                                             
   1997:  1,935,434 Accumulation Units @ 37.054456.........      $71,716,451                   
   1996:  1,944,411 Accumulation Units @ 32.542621.........                     $63,276,230    
                                                                                               
  International Equity Division                                                                
   1997:  23,069,550 Accumulation Units @ 1.938399.........       44,717,992                   
   1996:  20,439,570 Accumulation Units @ 1.726413.........                      35,287,138    
                                                                                               
  Growth Stock Division                                                                        
   1997:  482,897 Accumulation Units @ 20.837268...........       10,062,263                   
   1996:  378,236 Accumulation Units @ 16.046821...........                       6,069,485    
                                                                                               
  Growth and Income Stock Division                                                             
   1997:  711,558 Accumulation Units @ 20.502206...........       14,588,507                   
   1996:  424,144 Accumulation Units @ 15.767435...........                       6,687,664    
                                                                                               
  Index 500 Stock Division                                                                     
   1997:  2,558,205 Accumulation Units @ 36.141676.........       92,457,808                   
   1996:  2,386,284 Accumulation Units @ 27.133645.........                      64,748,577    
                                                                                               
  Balanced Division                                                                            
   1997:  1,341,930 Accumulation Units @ 71.490869.........       95,935,733                   
   1996:  1,489,658 Accumulation Units @ 58.832423.........                      87,640,161    
                                                                                               
  High Yield Bond Division                                                                     
   1997:  235,585 Accumulation Units @ 16.692972...........        3,932,608                   
   1996:  119,423 Accumulation Units @ 14.408967...........                       1,720,768    
                                                                                               
  Select Bond Division                                                                         
   1997:  85,036 Accumulation Units @ 83.938645............        7,137,800                   
   1996:  97,868 Accumulation Units @ 76.681608............                       7,504,704    
                                                                                               
  Money Market Division                                                                        
   1997:  38,584 Accumulation Units @ 27.434762............        1,058,532                   
   1996:  57,013 Accumulation Units @ 26.011476............                       1,483,002    
</TABLE>

    The Accompanying Notes are an Integral Part of the Financial Statements.


                                                                        25

<PAGE>   26

                 The Northwestern Mutual Life Insurance Company
                                   Form 10-K



Item 8. (continued)

                         NML VARIABLE ANNUITY ACCOUNT C
                      STATEMENT OF ASSETS AND LIABILITIES



<TABLE>
<CAPTION>
                                                                                 December 31
                                                                     -----------------------------------
Equity (Cont'd.)                                                           1997               1996
                                                                     -----------------  ----------------
<S>                                                                  <C>                <C>
 Contracts Issued After December 16, 1981 and Prior to May 1, 1984:
  Aggressive Growth Stock Division
   1997:  1,141 Accumulation Units @ 35.791674.....................  $          40,847
   1996:  4,243 Accumulation Units @ 31.591115.....................                     $        134,035
   Annuity Reserves................................................             33,487            31,590
                                                                     -----------------  ----------------
                                                                                74,334           165,625
                                                                     -----------------  ----------------
  International Equity Division
   1997:  109,646 Accumulation Units @ 1.893664....................            207,632
   1996:  109,569 Accumulation Units @ 1.695019....................                              185,722
   Annuity Reserves................................................             17,392            16,637
                                                                     -----------------  ----------------
                                                                               225,024           202,359
                                                                     -----------------  ----------------
  Growth Stock Division
   1997:  137 Accumulation Units @ 20.458788.......................              2,809
   1996:  N/A......................................................                                    0
   Annuity Reserves................................................             40,850                 0
                                                                     -----------------  ----------------
                                                                                43,659                 0
                                                                     -----------------  ----------------
  Growth and Income Stock Division
   1997:  2,270 Accumulation Units @ 20.129770.....................             45,701
   1996:  1,252 Accumulation Units @ 15.558532.....................                               19,472
   Annuity Reserves................................................                  0            33,791
                                                                     -----------------  ----------------
                                                                                45,701            53,263
                                                                     -----------------  ----------------
  Index 500 Stock Division
   1997:  19,041 Accumulation Units @ 34.906216....................            664,652
   1996:  45,781 Accumulation Units @ 26.337300....................                            1,205,748
   Annuity Reserves................................................             42,741            34,467
                                                                     -----------------  ----------------
                                                                               707,393         1,240,215
                                                                     -----------------  ----------------
  Balanced Division
   1997:  86,634 Accumulation Units @ 66.012286....................          5,718,908
   1996:  90,172 Accumulation Units @ 54.595947....................                            4,923,025
   Annuity Reserves................................................            486,559           429,289
                                                                     -----------------  ----------------
                                                                             6,205,467         5,352,314
                                                                     -----------------  ----------------
  Select Bond Division
   1997:  532 Accumulation Units @ 77.468103.......................             41,227
   1996:  7,598 Accumulation Units @ 71.125132.....................                              540,440
   Annuity Reserves................................................             40,290            39,535
                                                                     -----------------  ----------------
                                                                                81,517           579,975
                                                                     -----------------  ----------------
  Money Market Division
   1997:  871 Accumulation Units @ 25.362364.......................             22,084
   1996:  14,233 Accumulation Units @ 24.167111....................                              343,966
   Annuity Reserves................................................              7,530             7,669
                                                                     -----------------  ----------------
                                                                                29,614           351,635
                                                                     -----------------  ----------------
</TABLE>

    The Accompanying Notes are an Integral Part of the Financial Statements.


                                                                        26
<PAGE>   27

                 The Northwestern Mutual Life Insurance Company
                                   Form 10-K



Item 8. (continued)

                         NML VARIABLE ANNUITY ACCOUNT C
                      STATEMENT OF ASSETS AND LIABILITIES


<TABLE>
<CAPTION>
                                                                        December 31
                                                               ------------------------------
Equity (cont'd)                                                     1997            1996
                                                               --------------  --------------
<S>                                                            <C>             <C>
 Contracts Issued After December 31, 1991 Front Load Version:

  Aggressive Growth Stock Division
   1997:  3,169,006 Accumulation Units @ 2.350498............  $    7,448,743
   1996:  3,197,341 Accumulation Units @ 2.077739............                    $  6,643,240

  International Equity Division
   1997:  3,021,349 Accumulation Units @ 1.880500............       5,681,647
   1996:  2,709,249 Accumulation Units @ 1.685759............                       4,567,140

  Growth Stock Division
   1997:  710,110 Accumulation Units @ 2.034708..............       1,444,866
   1996:  587,482 Accumulation Units @ 1.577134..............                         926,538

  Growth and Income Stock Division
   1997:  1,970,478 Accumulation Units @ 2.001981............       3,944,860
   1996:  1,357,354 Accumulation Units @ 1.549666............                       2,103,446

  Index 500 Stock Division
   1997:  3,966,706 Accumulation Units @ 2.563560............      10,168,888
   1996:  3,880,961 Accumulation Units @ 1.937139............                       7,517,961

  Balanced Division
   1997:  6,187,478 Accumulation Units @ 1.931409............      11,950,551
   1996:  5,934,240 Accumulation Units @ 1.599774............                       9,493,443

  High Yield Bond Division
   1997:  423,726 Accumulation Units @ 1.630023..............         690,684
   1996:  275,323 Accumulation Units @ 1.416152..............                         389,899

  Select Bond Division
   1997:  2,574,248 Accumulation Units @ 1.490112............       3,835,918
   1996:  2,676,832 Accumulation Units @ 1.370157............                       3,667,680

  Money Market Division
   1997:  1,710,473 Accumulation Units @ 1.249188............       2,136,703
   1996:  2,829,669 Accumulation Units @ 1.192105............                       3,373,263
</TABLE>

    The Accompanying Notes are an Integral Part of the Financial Statements.



                                                                        27

<PAGE>   28

                 The Northwestern Mutual Life Insurance Company
                                   Form 10-K



Item 8. (continued)

                         NML VARIABLE ANNUITY ACCOUNT C
                      STATEMENT OF ASSETS AND LIABILITIES


<TABLE>
<CAPTION>
                                                                            December 31
                                                                    ----------------------------
Equity (cont'd)                                                         1997           1996
                                                                    -------------  -------------
<S>                                                                 <C>            <C>
 Contracts Issued After December 31, 1991 Simplified Load Version:

  Aggressive Growth Stock Division
   1997:  8,989,193 Accumulation Units @ 3.598431.................  $  32,346,992
   1996:  7,872,553 Accumulation Units @ 3.199964.................                 $  25,191,889

  International Equity Division
   1997:  7,247,144 Accumulation Units @ 1.828649.................     13,252,483
   1996:  5,703,032 Accumulation Units @ 1.649102.................                     9,404,881

  Growth Stock Division
   1997:  2,159,985 Accumulation Units @ 1.990509.................      4,299,469
   1996:  1,742,522 Accumulation Units @ 1.552125.................                     2,704,613

  Growth and Income Stock Division
   1997:  4,547,004 Accumulation Units @ 1.958555.................      8,905,558
   1996:  2,769,823 Accumulation Units @ 1.525144.................                     4,224,380

  Index 500 Stock Division
   1997:  9,442,314 Accumulation Units @ 3.240055.................     30,593,616
   1996:  8,015,553 Accumulation Units @ 2.463008.................                    19,742,371

  Balanced Division
   1997:  6,839,439 Accumulation Units @ 5.796067.................     39,641,848
   1996:  5,971,232 Accumulation Units @ 4.829655.................                    28,838,992

  High Yield Bond Division
   1997:  1,219,819 Accumulation Units @ 1.594619.................      1,945,147
   1996:  626,090 Accumulation Units @ 1.393713...................                       872,590

  Select Bond Division
   1997:  1,034,899 Accumulation Units @ 6.768475.................      7,004,691
   1996:  966,414 Accumulation Units @ 6.260939...................                     6,050,655

  Money Market Division
   1997:  5,844,682 Accumulation Units @ 2.339812.................     13,675,458
   1996:  3,818,067 Accumulation Units @ 2.246287.................                     8,576,475
                                                                    -------------  -------------
       Total Equity...............................................  $ 547,988,525  $ 426,652,571
                                                                    -------------  -------------
       Total Liabilities and Equity...............................  $ 551,112,386  $ 428,367,848
                                                                    =============  =============
</TABLE>

    The Accompanying Notes are an Integral Part of the Financial Statements.


                                                                        28
<PAGE>   29

                 The Northwestern Mutual Life Insurance Company
                                   Form 10-K



Item 8. (continued)

                         NML VARIABLE ANNUITY ACCOUNT C
             COMBINED STATEMENT OF OPERATIONS AND CHANGES IN EQUITY
                        For the Years Ended December 31


<TABLE>
<CAPTION>
                                                                            1997            1996            1995      
                                                                       --------------  --------------  -------------- 
<S>                                                                    <C>             <C>             <C>            
Investment Income                                                                                                     
 Dividend Income..................................................     $  27,689,163   $  16,994,370   $   6,470,776  
 Annuity Rate and Expense Guarantees..............................         2,501,975       1,738,625         856,764  
                                                                       -------------   -------------   -------------  
 Net Investment Income............................................        25,187,188      15,255,745       5,614,012  
                                                                       -------------   -------------   -------------  
Realized and Unrealized Gain (Loss) on Investments                                                                    
 Net Realized Gain (Loss) on Investments..........................        18,686,284       8,855,390       9,884,364  
 Unrealized Appreciation (Depreciation) During the Year...........        44,241,434      29,832,124      53,407,857  
                                                                       -------------   -------------   -------------  
 Net Gain (Loss) on Investments...................................        62,927,718      38,687,514      63,292,221  
                                                                       -------------   -------------   -------------  
Increase in Equity Derived from Investment Activity...............        88,114,906      53,943,259      68,906,233  
                                                                       -------------   -------------   -------------  
Equity Transactions                                                                                                   
 Contract Owners' Net Payments....................................        91,195,224      89,650,916      59,390,267  
 Surrenders and Other (Net).......................................       (57,974,180)    (34,747,640)    (60,872,729) 
                                                                       -------------   -------------   -------------  
Increase (Decrease) in Equity Derived from Equity Transactions ...        33,221,044      54,903,276      (1,482,462) 
                                                                       -------------   -------------   -------------  
Net Increase in Equity............................................       121,335,950     108,846,535      67,423,771  
Equity, Beginning of Year.........................................       426,652,573     317,806,038     250,382,267  
                                                                       -------------   -------------   -------------  
Equity, End of Year...............................................     $ 547,988,523   $ 426,652,573   $ 317,806,038  
                                                                       =============   =============   =============  
</TABLE>

    The Accompanying Notes are an Integral Part of the Financial Statements.

                                                                        29

<PAGE>   30

                 The Northwestern Mutual Life Insurance Company
                                   Form 10-K



Item 8. (continued)

                         NML VARIABLE ANNUITY ACCOUNT C
                         NOTES TO FINANCIAL STATEMENTS

Note 1--NML Variable Annuity Account C (the "Account") is a segregated asset
account of The Northwestern Mutual Life Insurance Company ("Northwestern Mutual
Life" or "Sponsor") used to fund variable annuity contracts ("contracts") for
HR-10 and corporate pension and profit-sharing plans which qualify for special
tax treatment under the Internal Revenue Code.  Beginning December 31, 1991,
two versions of the contract are offered:  Front Load contracts with a sales
charge up to 4.5% of purchase payments and Simplified Load contracts with an
installation fee of $750.

Note 2--The preparation of the financial statements in conformity with
generally accepted accounting principles requires management to make estimates
and assumptions that affect the reported amounts of assets and liabilities and
disclosure of contingent assets and liabilities at the date of the financial
statements and the reported amounts of revenues and expenses during the
reporting period.  Actual results could differ from those estimates.  Principal
accounting policies are summarized below.

Note 3--All assets of each Division of the Account are invested in shares of
the corresponding Portfolio of Northwestern Mutual Series Fund, Inc. (the
"Fund").  The shares are valued at the Fund's offering and redemption price per
share.

On May 3, 1994, five new portfolios commenced operations in the Fund:
Aggressive Growth Stock Portfolio, International Equity Portfolio, Growth Stock
Portfolio, Growth and Income Stock Portfolio and High Yield Bond Portfolio.
Additionally, on May 3, 1994, the assets of Northwestern Mutual Life's Variable
Annuity funds were merged into the respective portfolio of the Fund in a
tax-free exchange of shares.

The Fund is an open-end investment company registered under the Investment
Company Act of 1940.

Note 4--Annuity reserves are based on published annuity tables with age
adjustment and benefit payments which reflect actual investment experience.
Annuity reserves are based on the 1983 Table with assumed interest rates of 3
1/2% or 5%.

Note 5--Dividend income from the Fund is recorded on the record date of the
dividends.  Transactions in Fund shares are accounted for on the trade date.
The basis for determining cost on sale of Fund shares is identified cost.
Purchases and sales of Fund shares for the years ended December 31 by each
Division are shown below:


<TABLE>
<CAPTION>
Purchases                          1997         1996         1995
- ---------                       -----------  -----------  -----------
<S>                             <C>          <C>          <C>
Aggressive Growth Division      $21,563,810  $30,690,195  $15,956,497
International Equity Division    14,484,423   15,119,614    6,724,373
Growth Stock Division             5,929,895    7,308,964    1,794,866
Growth & Income Stock Division   18,445,529    8,410,421    3,709,640
Index 500 Stock Division         22,292,577   19,824,136    9,719,794
Balanced Division                18,920,420   19,426,753   17,257,735
High Yield Bond Division          4,398,102    2,362,508      632,095
Select Bond Division              4,295,571    5,445,050    4,302,192
Money Market Division            20,035,837   20,346,897   10,821,340


Sales
- -----
Aggressive Growth Division      $12,675,291  $ 1,045,256  $ 6,866,522
International Equity Division     4,352,840    1,571,810    4,899,939
Growth Stock Division             2,395,716      303,927      213,213
Growth & Income Stock Division    2,674,188      839,196      310,894
Index 500 Stock Division         10,114,507    5,253,981    7,360,855
Balanced Division                17,783,563   29,797,911   29,565,575
High Yield Bond Division            480,911      158,086       87,219
Select Bond Division              4,561,008    3,918,139    4,475,998
Money Market Division            16,919,905   15,887,232   13,008,176
</TABLE>


                                                                        30

<PAGE>   31

                 The Northwestern Mutual Life Insurance Company
                                   Form 10-K



Item 8. (continued)

                                                                         
                        NML VARIABLE ANNUITY ACCOUNT C
                        NOTES TO FINANCIAL STATEMENTS
                                                                         

Note 6--On April 30, 1993, Northwestern Mutual Capital Appreciation Stock Fund
was merged into the Northwestern Mutual Index 500 Stock Fund in a tax-free
exchange of fund shares.  23,586,477 shares of Northwestern Mutual Capital
Appreciation Stock Fund, Inc. were exchanged for 24,739,593 shares of
Northwestern Mutual Index 500 Stock Fund, Inc.  The shares exchanged were
valued at $33,406,725 for each Division.

Note 7--A deduction for annuity rate and expense guarantees is determined daily
and paid to Northwestern Mutual Life as compensation for assuming the risk that
annuity payments will continue for longer periods than anticipated because the
annuitants as a group live longer than expected and the risk that the charges
made by Northwestern Mutual Life may be insufficient to cover the actual costs
incurred in connection with the contracts.

Generally, for contracts issued after December 31, 1991, for the Front Load
Version and the Simplified Load Version, the deduction for annuity rate and
expense guarantees if determined daily at annual rates of 6.5/10 of 1% and 1
1/4%, respectively, of the net assets of each Division attributable to these
contracts and is paid to Northwestern Mutual Life.  For these contracts, the
rates may be increased or decreased by the Board of Trustees of Northwestern
Mutual Life not to exceed 1% and 1 1/2% annual rates, respectively.

Generally, the deduction for contracts issued before December 17, 1981 or
between April 30, 1984 and December 31, 1991, as provided for in the contracts
has been waived by the Board of Trustees of Northwestern Mutual Life.  For
these contracts, the rate may be determined by the Board of Trustees of
Northwestern Mutual Life not to exceed a  1/4 of 1% annual rate.

For contracts issued after December 16, 1981, and prior to May 1, 1984, the
deduction is determined daily at an annual rate of  1/2 of 1% of the net assets
of each Division attributable to these contracts and is paid to Northwestern
Mutual Life.  For these contracts, the rate may be increased or decreased by
the Board of Trustees of Northwestern Mutual Life not to exceed a  3/4 of 1%
annual rate.

Since 1996, Northwestern Mutual Life has paid a dividend to certain contracts.
The dividend is re-invested in the Account and has been reflected as a Contract
Owners' Net Payment in the accompanying financial statements.

Note 8--Northwestern Mutual Life is taxed as a "life insurance company" under
the Internal Revenue Code and the operations of the Account form a part of and
are taxed with those of Northwestern Mutual Life.  Under current law, no
federal income taxes are payable with respect to the Account.   Accordingly, no
provision for any such liability has been made.



                             Item 9 is on page 34.


                                                                        31

<PAGE>   32

                 The Northwestern Mutual Life Insurance Company
                                   Form 10-K




Item 9.  Disagreements on Accounting and Financial Disclosure

         Not applicable.




                             Item 10 is on page 35.

                                                                        32


<PAGE>   33

                 The Northwestern Mutual Life Insurance Company
                                   Form 10-K



                                    PART III

Item 10. Directors and Executive Officers of the Registrant

         (a)  The following information as of March 1, 1998, is provided with
              respect to each director, including persons chosen to become
              directors, of the Registrant.  The Registrant uses the title of
              Trustee to denote the directors.




<TABLE>
<CAPTION>
                                             EXPIRATION OF TERM
        TRUSTEE           AGE  YEAR ELECTED  OF OFFICE                            OTHER POSITIONS PRESENTLY HELD WITH REGISTRANT
- ------------------------  ---  ------------  --------------------  -----------------------------------------------------------------
<S>                       <C>  <C>           <C>                   <C>
R. Quintus Anderson       67       1984      May 1999              Chairman, Audit Committee
Edward E. Barr            61       1991      May 1999              Member, Human Resources and Public Policy Committee
Gordon T. Beaham, III     66       1988      May 2001              Member, Operations and Technology Committee
Robert C. Buchanan        57       1991      May 1999              Member, Audit, Executive and Finance Committees
Robert E. Carlson         62       1989      May 1998 (1)          Executive Vice President; Member, Executive Committee
George A. Dickerman       59       1994      May 2000              Member, Agency and Marketing Committee
Pierre S. DuPont          63       1985      May 1998 (1)          Member, Agency and Marketing Committee
James D. Ericson          62       1989      May 2000              President and C.E.O.; Member, Human Resources and Public Policy,
                                                                   Agency & Marketing, and Operations and Technology Committees;
                                                                   Chairman, Executive and Finance Committees
J. E. Gallegos            62       1985      May 2000              Member, Audit Committee
Stephen N. Graff          63       1996      May 2000              Member, Executive, Finance, and Operations and Technology
                                                                   Committees 
Patricia Albjerg Graham   63       1980      May 2000              Member, Human Resources and Public Policy Committee
Stephen F. Keller         59       1984      May 1999              Member, Human Resources and Public Policy Committee
Barbara A. King           51       1996      May 1998 (1)          Member, Agency and Marketing Committtee
J. Thomas Lewis           61       1978      May 1998 (1)          Chairman, Human Resources  and Public Policy Committee
Daniel F. McKeithan, Jr.  62       1988      May 1999              Member, Executive, Finance, and Human Resources and Public Policy
                                                                   Committees 
</TABLE>

(1)  Candidate proposed for re-election by the Board of Trustees for the
     election to be held at the May 1998 Annual meeting of policyholders.  If
     re-elected, these Trustees' terms will expire in May of 2002.


                                                                        33
<PAGE>   34

                 The Northwestern Mutual Life Insurance Company
                                   Form 10-K





<TABLE>
<CAPTION>
                                           EXPIRATION OF TERM
       TRUSTEE          AGE  YEAR ELECTED  OF OFFICE                       OTHER POSITIONS PRESENTLY HELD WITH REGISTRANT
- ----------------------  ---  ------------  --------------------  -------------------------------------------------------------------
<S>                     <C>  <C>           <C>                   <C>
Guy A. Osborn           62       1994      May 2001              Member, Operations and Technology, Executive and Finance Committees
Timothy D. Proctor      48       1997      May 2001              Member, Audit Committee
Donald J. Schuenke      69       1980      May 1998 (1)          Member, Agency and Marketing, Executive and Finance Committees
H. Mason Sizemore, Jr.  56       1993      May 1999              Member, Agency and Marketing Committee
Harold B. Smith         64       1973      May 2000              Member, Operations and Technology Committee
Sherwood H. Smith, Jr.  61       1992      May 1998 (1)          Chairman, Agency and Marketing Committee
John E. Steuri          58       1994      May 1999              Chairman, Operations and Technology Committee
John J. Stollenwerk     58       1993      May 2001              Member, Agency and Marketing, Executive and Finance Committees
Barry L. Williams       53       1987      May 2001              Member, Human Resources and Public Policy Committee
Kathryn D. Wriston      59       1986      May 2001              Member, Audit Committee
</TABLE>

(1)  Candidate proposed for re-election by the Board of Trustees for the
     election to be held at the May 1998 Annual meeting of policyholders.  If
     re-elected, these Trustees' terms will expire in May of 2002.


                                                                        34

<PAGE>   35

                 The Northwestern Mutual Life Insurance Company
                                   Form 10-K



Item 10. (continued)

       (b)  The following information as of March 1, 1998, is provided
            with respect to each Executive Officer of the Registrant.



<TABLE>
<CAPTION>
        NAME          AGE                                POSITION
- --------------------  ---  ---------------------------------------------------------------------
<S>                   <C>  <C>
James D. Ericson      62   President and Chief Executive Officer, Trustee
Robert E. Carlson     62   Executive Vice President (Strategic Marketing), Trustee
Peter W. Bruce        52   Executive Vice President (Accumulation Products and Long-Term Care)
Frederic H. Sweet     54   Senior Vice President (Government Relations)
Dennis Tamcsin        59   Senior Vice President (Field Relations)
James W. Ehrenstrom   61   Senior Vice President
Walt J. Wojcik        58   Senior Vice President (Information Systems)
Edward J. Zore        52   Executive Vice President (Life and Disability Income Insurance)
Mason G. Ross         53   Senior Vice President (Investment Administration and Real Estate)
Richard L. Hall       52   Senior Vice President (Life and Disability Income Market Development)
John M. Bremer        50   Executive Vice President, General Counsel and Secretary
                           (Administration and Law)
Mark G. Doll          48   Senior Vice President (Public Markets)
William C. Koenig     50   Senior Vice President and Chief Actuary
Gary E. Long          53   Vice President and Controller
Deborah A. Beck       50   Senior Vice President (Insurance Operations/Chief Compliance Officer)
Donald L. Mellish     59   Senior Vice President (Field Financial Services)
Barbara F. Piehler    47   Vice President (Policyowner Services)
James F. Reiskytl     60   Vice President (Tax and Financial Planning)
Leonard F. Stecklein  51   Senior Vice President (Agency Services)
Martha M. Valerio     51   Vice President (Corporate Development)
W. Ward White         58   Vice President (Communications)
Thomas E. Dyer        52   Vice President (New Business)
Steven T. Catlett     48   Vice President (Corporate Services)
Gregory C. Oberland   40   Vice President (Policy Benefits)
Meridee J. Maynard    42   Vice President (Annuity and Accumulation Products)
Susan A. Lueger       44   Vice President (Human Resources)
William H. Beckley    50   Senior Vice President (Agencies)
Robert J. Berdan      51   Vice President (Compliance/Best Practices)
John E. Schlifske     38   Vice President (Securities)
Bruce L. Miller       51   Senior Vice President (Corporate Planning and Development)
</TABLE>

            All of the Executive Officers, except Susan A. Lueger and Bruce L.
            Miller, have been associated with the Registrant, although not
            necessarily in their present positions, for more than five years.

            Susan A. Lueger has been Vice President of NML since May, 1994;
            Vice President of Human Resources at Wisconsin Electric Power
            Company 1992-1994; prior thereto with WEPC in the following
            positions:  Assistant Vice President-Human Resources 1/92 to 11/92;
            Director-Human Resources 5/91 to 1/92; Manager-Compensation &
            Benefits Division 7/90 to 5/91; Project Specialist-Employment and
            Training Division 2/88 to 7/90.  Bruce L. Miller has been Senior
            Vice President of NML since july, 1996.  Prior thereto consultant
            for Medication Delivery Services 1995-96; CoreSource, Inc. 1992-94;
            Crabtree Capital Corporation 1989-92; Aon Corporation 1980-89;
            Glover, Inc. 1977-80; Whitman Corporation 1973-77; McKinsey &
            Company, Inc. 1966-73.


                                                                        35

<PAGE>   36

                 The Northwestern Mutual Life Insurance Company
                                   Form 10-K




Item 10.  (continued)

          Term of office for all Executive Officers is one year expiring May 31,
          1998. 

          (c)  Not applicable

          (d)  No one of the Executive Officers or Trustees is related to any
               other to the best of our knowledge.

          (e)  Business experience and directorships of Trustees are as
               follows:





<TABLE>
<CAPTION>
                                                  PRINCIPAL OCCUPATION
        TRUSTEE                                  DURING PAST FIVE YEARS                                    DIRECTORSHIPS
- ----------------------------------------------------------------------------------------------------------------------------------
<S>                       <C>                                                                    <C>
R. Quintus Anderson       Chairman, The Aarque Capital Corporation, Jamestown, New York, since   Cold Metal Products Company, Inc.
                          1966.  Chairman, The Aarque Companies, 1980-1996.                      Oneida, Ltd.

                                                                                                                        
Edward E. Barr            Chairman, Sun Chemical Corporation, Fort Lee, New Jersey.              First Union Corporation
                                                                                                 United Water Resources 

Gordon T. Beaham, III     Chairman and President, Faultless Starch/Bon Ami Company, Kansas
                          City, Missouri, since 1987.  Prior thereto, President and Chief
                          Executive Officer.

Robert C. Buchanan        President and Chief Executive Officer, Fox Valley Corporation,         Grady, W. H. Company
                          Appleton, Wisconsin.                                                   Firstar Corporation

Robert E. Carlson         Executive Vice President of NML since 1987.  Senior Vice President
                          1982-1987.  Prior thereto, Vice President-Research, Life Insurance
                          Marketing and Research Association, Farmington, Connecticut.

George A. Dickerman       Chairman of the Board, Spalding Sports Worldwide, Chicopee,            Evenflo & Spalding Holdings Corp.
                          Massachusetts, since 1981.                                             
                                                                                                 
Pierre S. Du Pont         Attorney, Richards, Layton & Finger, Wilmington, Delaware, since       Louisiana-Pacific Corporation
                          1985; prior thereto, Governor of Delaware.                             Pet Incorporated
                                                                                                 Whitman Corporation

James D. Ericson          President and Chief Executive Officer of NML since 10-1-93.            MGIC Investment Corporation
                          President and Chief Operating Officer 1991-1993.  President            Kohl's Corporation
                          1990-1991; Executive Vice President 1987-1990; prior thereto, Senior   Consolidated Paper Inc.
                          Vice President-Investments 1980-1987.                                  Mason Street Funds, Inc.

J. E. Gallegos            Attorney, Gallegos Law Firm, Santa Fe, New Mexico since 1988; prior
                          thereto, Chairman of the Board, Enviromed Inc., Santa Fe, New
                          Mexico, since 1987; prior thereto, President, Jones, Gallegos, Snead
                          & Wertheim, P.A., Santa Fe, New Mexico.


</TABLE>
                                                                        36

<PAGE>   37

                 The Northwestern Mutual Life Insurance Company
                                   Form 10-K

<TABLE>
<CAPTION>
                                                  PRINCIPAL OCCUPATION
        TRUSTEE                                  DURING PAST FIVE YEARS                                    DIRECTORSHIPS
- ----------------------------------------------------------------------------------------------------------------------------------
<S>                       <C>                                                                    <C>
Stephen N. Graff          Office Managing Partner (retired), Arthur Andersen LLP, Milwaukee,     Mason Street Funds, Inc. 
                          Wisconsin, since 1994.  Managing Partner (Milwaukee office) 1981-93;   Regal-Beloit Corporation 
                          head of Audit Division 1978-81.                                        

Patricia Albjerg Graham   President, Spencer Foundation, Chicago, Illinois, since 1991; and
                          Professor of the History of American Education, Harvard University,
                          Cambridge, Massachusetts, since 1974.  Dean of the Graduate School
                          of Education at Harvard 1982-1991.

Stephen F. Keller         Former Chairman, The Santa Anita Companies, and Attorney, Los
                          Angeles, California, since August 1996.  Chairman, The Santa Anita
                          Companies, 1993-1996.  Chairman, Santa Anita Realty Enterprises; and
                          President, Santa Anita Operating Company, Arcadia, California,
                          1992-1993.  President and C.O.O., The Santa Anita Companies,
                          Arcadia, California, 7/91 to 1/92.  Attorney, Fulbright & Jaworski,
                          Los Angeles, California, 1/91 to 7/91.  attorney, Seidler, Amdec
                          Securities, Inc., Los Angeles, California 1987-1991.  Prior thereto,
                          Attorney, Lillick McHose & Charles, Los Angeles, California.

Barbara A. King           President, Landscape Structures, Inc., Delano, Minnesota, since 1973.

J. Thomas Lewis           Attorney, Monroe & Lemann, New Orleans, Louisiana.
                                                                                                 
Daniel F. McKeithan, Jr.  President, Tamarack Petroleum Co. Inc., Milwaukee, Wisconsin, since    Firstar Corporation
                          1982.                                                                  Marcus Corporation 
                                                                                                 WICOR Corporation

Guy A. Osborn             Retired Chairman, Universal Foods Corp., Milwaukee, Wisconsin, since   Firstar Corporation        
                          April 1997.  Chairman, October 1996-1997.  Chairman and Chief          Firstar Bank Milwaukee     
                          Executive Officer, 1990-1996.  Prior thereto, Chief Executive          Fleming Cos.               
                          Officer 1988-1990.                                                     Universal Foods Corporation
                                                                                                 WICOR                      
                                                                                                 Wisconsin Gas Company      

Timothy D. Proctor        Senior Vice President Human Resources, General Counsel and
                          Secretary, Glaxo Wellcome Inc., since 1996.  Senior Vice President,
                          General Counsel and Secretary, 1994-1996; Vice President and General
                          Counsel, 1993-1994.  Prior thereto Vice President and Associate
                          General Counsel, Merck & Co., Inc., 1980-1993.


</TABLE>


                                                                        37

<PAGE>   38

                 The Northwestern Mutual Life Insurance Company
                                   Form 10-K


<TABLE> 
<CAPTION>
                                                  PRINCIPAL OCCUPATION
        TRUSTEE                                  DURING PAST FIVE YEARS                                    DIRECTORSHIPS
- ----------------------------------------------------------------------------------------------------------------------------------
<S>                      <C>                                                                     <C>
Donald J. Schuenke        Chairman of the Board, Northern Telecom Limited since April 1994.      A. O. Smith Corporation     
                          Retired Chairman of NML since 2-1-94.  Chairman of the Board of NML    Badger Meter, Inc.          
                          10-1-93 to 1-31-94.  Chairman and Chief Executive Officer 1990-1993.   Federal Home Loan Mortgage  
                           President and Chief Executive Officer 1983-1990; President and        Corporation (Freddie Mac)   
                          Chief Operating Officer 1981-1983; President 1980-1981; prior          Northern Telecom, Ltd.      
                          thereto, Senior Vice President-Investments.                            

H. Mason Sizemore, Jr.    President and Chief Operating Officer, The Seattle Times, Seattle,
                          Washington since 1985.
                                                                                                 
Harold B. Smith           Chairman, Executive Committee, Illinois Tool Works Inc., Glenview,     Grainger, W. W., Inc.     
                          Illinois since 1982; Vice Chairman, 1981; prior thereto, President.    Illinois Tool Works Inc.  
                                                                                                 Northern Trust Corporation
                                                                                                                           
Sherwood H. Smith, Jr.    Chairman of the Board, Carolina Power & Light Company, Raleigh,        Carolina Power & Light Co.
                          North Carolina, since October 1996.  Chairman and Chief Executive      Northern Telecom Ltd.
                          Officer, 1992-1996.  Prior thereto, Chairman/President and CEO         Springs Industries, Inc.
                          1980-1992; President and CEO 1979-1980; President 1976-1979.           Wachovia Corporation


John E. Steuri            Chairman, Advanced Thermal Technologies, Little Rock, Arkansas,        National Computer Systems
                          since May 1997.  Retired Chairman and CEO *ALLTEL Information
                          Services, Inc., Little Rock, Arkansas, 1996-1997.  Chairman and CEO
                          1989-1996.                                                             

                                                                                                 
John J. Stollenwerk       President and Owner, Allen-Edmonds Shoe Corporation, Port              Badger Meter, Inc.         
                          Washington, Wisconsin since 1980.                                      Firstar Bank Milwaukee N.A.
                                                                                                 Koss Corporation           

Barry L. Williams         President and Chief Executive Officer, Williams Pacific Ventures,      American President Companies  
                          Inc., San Francisco, California, since 1/1993.  Prior thereto:         Pacific Gas & Electric        
                          President 1987-1992; President and Chief Executive Officer, C. N.      Simpson Manufacturing Company 
                          Flagg Power, Inc., Meriden, Connecticut 1988-1992.  Prior thereto,     Tenera L.P.                   
                          Managing Principal, Bechtel Investments, Inc. and Sequoia                                            
                          Investments, Inc., San Francisco, California.                                                        

Kathryn D. Wriston        Director of various corporations.                                      Santa Fe Energy Resources
                                                                                                 Stanley Works, The

</TABLE>

*    Note:  Prior to 2/15/95, this company was known as Systematics
     Information Services, Inc.


                                                                        38

<PAGE>   39

                 The Northwestern Mutual Life Insurance Company
                                   Form 10-K



Item 10. (continued)

       (f)  To the best of the Registrant's knowledge, none of the
            Registrant's Executive Officers or Trustees have been involved in
            any of the items required to be reported in response to Item 401(f)
            of Regulation S-K.

       (g)  Not applicable.





                             Item 11 is on page 42.



                                                                        39

<PAGE>   40

                 The Northwestern Mutual Life Insurance Company
                                   Form 10-K



Item 11. Executive Compensation

     Not applicable. NML Variable Annuity Accounts A and C have no directors or
executive officers, the Executive Officers and Trustees of The Northwestern
Mutual Life Insurance Company spend no substantial portion of their time on
matters relating to NML Variable Annuity Accounts A and C, and the amounts of
compensation received by the Executive Officers and Trustees of The
Northwestern Mutual Life Insurance Company have no bearing on the values
associated with variable annuity contracts issued in connection with
Northwestern Mutual Variable Annuity Accounts A and C.


                                                                        40

<PAGE>   41

                 The Northwestern Mutual Life Insurance Company
                                   Form 10-K



Item 12. Security Ownership of Certain Beneficial Owners and Management

         (a)  Not applicable.  The Registrant is a mutual life insurance
              company and has no stockholders as such.

         (b)  Not applicable.

         (c)  Not applicable.





                             Item 13 is on page 44.

                                                                        41

<PAGE>   42

                 The Northwestern Mutual Life Insurance Company
                                   Form 10-K




Item 13.  Certain Relationships and Related Transactions

       (a)  (1)  The Registrant's second-tier subsidiary, Northwestern Mutual
                 Investment Services, Inc. ("NMIS"), serves as the investment
                 advisor to Northwestern Mutual Series Fund, Inc. and Mason
                 Street Funds, Inc. (the "Funds"), series companies registered
                 as open-end management companies under the Investment Company
                 Act of 1940 and each consisting of nine portfolios; and the
                 Registrant is a party to investment advisory agreements with
                 both funds.  The investment advisory agreements were entered
                 into or renewed during the fiscal year.  Various Trustees and
                 Officers of the Registrant serve as directors and officers of
                 the Funds and may be deemed to have a direct or indirect
                 material interest in the existence of the              
                 investment advisory agreements. 


            (2)  Various Trustees and Officers of the Registrant
                 have securities accounts with Robert W. Baird and  Co.
                 Incorporated ("Baird") and effected transactions through such
                 accounts during the fiscal year. Baird is a regional
                 broker-dealer firm and a member of the New York Stock
                 Exchange.  Baird is a majority-owned indirect subsidiary of
                 the Registrant.


                                                                        42

<PAGE>   43

                 The Northwestern Mutual Life Insurance Company
                                   Form 10-K



Item 13. (continued)

       (b)  Not applicable.

       (c)  Loans are made to Trustees and officers in accordance with
            the provisions of insurance policies which they may own.  Such
            loans are made in the ordinary course of business and are
            administered solely according to the terms of the policy.

       (d)  Not applicable.  The Registrant was not organized within
            the past five years.




                             Item 14 is on page 46.

                                                                        43


<PAGE>   44

                 The Northwestern Mutual Life Insurance Company
                                   Form 10-K




<TABLE>
<S><C>
Item 14.  Exhibits, Financial Statement Schedules, and Reports on Form 8-K         Page

          (a) Financial Statements and Exhibits                                     16

              (1)  NML Variable Annuity Account A (in Part II, Item  8)
                     Statement of Assets and Liabilities,
                          December 31, 1997 and 1996
                     Statement of Operations and Changes in
                          Equity, for years ended December 31,
                          1997, 1996 and 1995
                     Notes to Financial
                          Statements
                     Report of Independent Accountants


              (2)  NML Variable  Annuity Account C (in Part II, Item 8)             25
                     Statement of Assets and Liabilities, December 31, 1997 
                          and 1996
                     Statement of Operations and Changes in
                          Equity, for years ended December 31,
                          1997, 1996 and 1995
                     Notes to Financial
                          Statements
                     Report of Independent Accountants
              (3)  The Northwestern Mutual Life Insurance Company                   47
                   Attached are:
                     Report of Independent Accountants
                     Consolidated Statement of Financial
                          Position, December 31, 1997 and 1996
                     Consolidated Statement of Operations, for
                          years ended December 31, 1997, 1996 and
                          1995
                     Consolidated Statement of General
                          Contingency Reserve, for years ended
                          December 31, 1997, 1996 and 1995
                     Consolidated Statement of Cash Flows, for
                          years ended December 31, 1997, 1996 and
                          1995
                     Notes to Financial
                          Statements

       (b)  No reports on Form 8-K have been filed during
            the last quarter of the year ended December 31, 1997.

       (c)  Compensation amounts deferred in 1997 are                        
            included as Exhibit I.                                                  65

            Financial Statements of majority owned subsidiaries
            of the Registrant not consolidated have been omitted
            because, considered in the aggregate as a single
            subsidiary, they do not constitute a significant
            subsidiary.

       (d)  Not applicable.



</TABLE>
                                                                        44

<PAGE>   45
THE NORTHWESTERN MUTUAL LIFE
INSURANCE COMPANY

CONSOLIDATED FINANCIAL STATEMENTS
GENERAL DISTRIBUTION

DECEMBER 31, 1997, 1996 AND 1995




<PAGE>   46





                       REPORT OF INDEPENDENT ACCOUNTANTS

To the Board of Trustees and Policyowners of
     The Northwestern Mutual Life Insurance Company


We have audited the accompanying consolidated statement of financial position
of The Northwestern Mutual Life Insurance Company and its subsidiary as of
December 31, 1997 and 1996, and the related consolidated statements of
operations, of changes in general contingency reserve and of cash flows for
each of the three years in the period ended December 31, 1997.  These
consolidated financial statements are the responsibility of the Company's
management.  Our responsibility is to express an opinion on these consolidated
financial statements based on our audits.

We conducted our audits in accordance with generally accepted auditing
standards.  Those standards require that we plan and perform the audit to
obtain reasonable assurance about whether the financial statements are free of
material misstatement.  An audit includes examining, on a test basis, evidence
supporting the amounts and disclosures in the financial statements.  An audit
also includes assessing the accounting principles used and significant
estimates made by management, as well as evaluating the overall financial
statement presentation.  We believe that our audits provide a reasonable basis
for our opinion.

In our report dated January 24, 1996, we expressed an opinion that the 1995
consolidated financial statements, prepared using accounting practices
prescribed or permitted by the Insurance Departments of the states in which the
Company and its subsidiary were domiciled (statutory basis of accounting), were
presented fairly, in all material respects, in conformity with generally
accepted accounting principles.  As described in Note 1 to these financial
statements, pursuant to the pronouncement of the Financial Accounting Standards
Board, financial statements of mutual life insurance enterprises prepared using
accounting practices prescribed or permitted by insurance regulators (statutory
basis of accounting) are no longer considered presentations in conformity with
generally accepted accounting principles.  Accordingly, our present opinion on
the presentation of the 1995 financial statements, as presented herein, is
different from that expressed in our previous report.





<PAGE>   47


As described in Note 1, these consolidated financial statements were prepared
in conformity with accounting practices prescribed or permitted by the Office
of the Commissioner of Insurance of the State of Wisconsin (statutory basis of
accounting), which practices differ from generally accepted accounting
principles.  Accordingly, the consolidated financial statements are not
intended to represent a presentation in accordance with generally accepted
accounting principles.  The effects on the consolidated financial statements of
the variances between the statutory basis of accounting and generally accepted
accounting principles, although not reasonably determinable, are presumed to be
material.

In our opinion, the consolidated financial statements audited by us (1) do not
present fairly in conformity with generally accepted accounting principles, the
financial position of The Northwestern Mutual Life Insurance Company and its
subsidiary at December 31, 1997 and 1996, or the results of their operations or
their cash flows for each of the three years in the period ended December 31,
1997 because of the effects of the variances between the statutory basis of
accounting and generally accepted accounting principles referred to in the
preceding paragraph and (2) do present fairly, in all material respects, the
financial position of The Northwestern Mutual Life Insurance Company and its
subsidiary at December 31, 1997 and 1996 and the results of their operations
and their cash flows for each of the three years in the period ended December
31, 1997, on the basis of accounting described in Note 1.



January 26, 1998





<PAGE>   48




                 THE NORTHWESTERN MUTUAL LIFE INSURANCE COMPANY
                  CONSOLIDATED STATEMENT OF FINANCIAL POSITION
                                 (in millions)


<TABLE>
<CAPTION>
                                                   December 31,
                                                 ----------------
                                                  1997     1996
                                                 ------    ------
                                   Assets

<S>                                              <C>      <C>
Bonds                                            $32,359  $29,076
Common and preferred stocks                        6,524    4,728
Mortgage loans                                    10,835    9,564
Real estate                                        1,372    1,385
Policy loans                                       7,163    6,802
Other investments                                  2,026    1,714
Cash and temporary investments                       572    1,131
Due and accrued investment income                    795      764
Other assets                                       1,275    1,177
Separate account assets                            8,160    6,339
                                                 -------  -------
              
      Total assets                               $71,081  $62,680
                                                 =======  =======
              
              
                 Liabilities and General Contingency Reserve
                           
              
Reserves for policy benefits                     $47,343  $43,209
Policy benefit and premium deposits                1,624    1,567
Policyowner dividends payable                      2,640    2,350
Interest maintenance reserve                         461      299
Asset valuation reserve                            1,974    1,538
Income taxes payable                               1,043      942
Other liabilities                                  3,735    2,921
Separate account liabilities                       8,160    6,339
                                                 -------  -------
                                                 
      Total liabilities                           66,980   59,165
                                                 
General contingency reserve                        4,101    3,515
                                                 -------  -------
                                                 
      Total liabilities and general              
        contingency reserve                      $71,081  $62,680
                                                 =======  =======
</TABLE>


                   The accompanying notes are an integral
                      part of the financial statements.

<PAGE>   49




                 THE NORTHWESTERN MUTUAL LIFE INSURANCE COMPANY
                      CONSOLIDATED STATEMENT OF OPERATIONS
                                 (in millions)

<TABLE>
<CAPTION>
                                                            For the year ended
                                                               December 31,
                                                          ----------------------
                                                           1997    1996    1995
                                                          ------  ------  ------
Revenue
<S>                                                       <C>     <C>     <C>
     Premiums                                             $7,294  $6,667  $6,196
     Net investment income                                 4,171   3,836   3,673
     Policy benefits left with Company and other income      861     759     733
                                                          ------  ------  ------

          Total revenue                                   12,326  11,262  10,602
                                                          ------  ------  ------

Benefits and expenses
     Benefit payments to policyowners and beneficiaries:
      Death benefits                                         775     673     655
      Surrender benefits                                   1,422   1,182   1,375
      Disability benefits                                    227     202     174
      Annuity benefits                                       140     128      92
      Matured endowments                                      58      52      48
      Payments from policy benefits left with Company        707     684     590
                                                          ------  ------  ------

          Benefits paid                                    3,329   2,921   2,934

     Net transfers to separate accounts                      566     579     236
     Net additions to policy reserves                      4,026   3,701   3,506
                                                          ------  ------  ------

          Total benefits                                   7,921   7,201   6,676

     Operating expenses                                    1,138   1,043   1,026
                                                          ------  ------  ------

          Total benefits and expenses                      9,059   8,244   7,702
                                                          ------  ------  ------

Gain from operations before income taxes and dividends     3,267   3,018   2,900

Policyowner dividends                                      2,636   2,341   2,111
                                                          ------  ------  ------

Gain from operations before taxes                            631     677     789
Income tax expense                                           356     452     467
                                                          ------  ------  ------

Net gain from operations                                     275     225     322
Net realized capital gains                                   414     395     137
                                                          ------  ------  ------

          Net income                                      $  689  $  620  $  459
                                                          ======  ======  ======
</TABLE>


                     The accompanying notes are an integral
                       part of the financial statements.


<PAGE>   50




                 THE NORTHWESTERN MUTUAL LIFE INSURANCE COMPANY
        CONSOLIDATED STATEMENT OF CHANGES IN GENERAL CONTINGENCY RESERVE
                                 (in millions)


<TABLE>
<CAPTION>
                                                      For the year ended
                                                         December 31,
                                                    ----------------------
                                                     1997    1996    1995
                                                    ------  ------  ------

     <S>                                            <C>     <C>     <C>
     Beginning of year balance                      $3,515  $2,786  $2,225

          Net income                                   689     620     459

          Increase in net unrealized capital gains     576     295     373

          Increase in investment reserves             (526)   (176)   (237)

          Other, net                                  (153)    (10)    (34)
                                                    ------  ------  ------

     Net increase in general contingency reserve       586     729     561
                                                    ------  ------  ------

     End of year balance                            $4,101  $3,515  $2,786
                                                    ======  ======  ======
</TABLE>



                     The accompanying notes are an integral
                       part of the financial statements.


<PAGE>   51




                 THE NORTHWESTERN MUTUAL LIFE INSURANCE COMPANY
                      CONSOLIDATED STATEMENT OF CASH FLOWS
                                 (in millions)

<TABLE>
<CAPTION>
                                                         For the year ended
                                                             December 31,
                                                      -------------------------
                                                        1997     1996     1995
                                                      -------  -------  -------
<S>                                                   <C>      <C>      <C>
Cash flows from operating activities
     Insurance and annuity premiums                    $8,093   $7,361   $6,864
     Investment income received                         3,928    3,634    3,480
     Net disbursement of policy loans                    (360)    (326)    (331)
     Benefits paid to policyowners and beneficiaries   (3,316)  (2,912)  (2,939)
     Net transfers to separate accounts                  (565)    (579)    (236)
     Policyowner dividends paid                        (2,347)  (2,105)  (1,945)
     Operating expenses and taxes                      (1,722)  (1,663)  (1,364)
     Other, net                                           564    1,558      381
                                                      -------  -------  -------

          Net cash provided by operating activities     4,275    4,968    3,910
                                                      -------  -------  -------

Cash flows from investing activities
     Proceeds from investments sold or matured
          Bonds                                        38,284   31,942   25,317
          Common and preferred stocks                   9,057    4,570    2,465
          Mortgage loans                                1,012    1,253      431
          Real estate                                     302      178       48
          Other invested assets                           398      316      149
                                                      -------  -------  -------

                                                       49,053   38,259   28,410
                                                      -------  -------  -------

     Cost of investments acquired
          Bonds                                        41,169   35,342   27,596
          Common and preferred stocks                   9,848    4,463    2,562
          Mortgage loans                                2,309    2,455    1,883
          Real estate                                     202      125      202
          Other invested assets                           359      255      336
                                                      -------  -------  -------

                                                       53,887   42,640   32,579
                                                      -------  -------  -------

          Net cash used in investing activities        (4,834)  (4,381)  (4,169)
                                                      -------  -------  -------

          Net (decrease) increase in cash
           and temporary investments                     (559)     587     (259)

Cash and temporary investments, beginning of year       1,131      544      803
                                                      -------  -------  -------

Cash and temporary investments, end of year           $   572  $ 1,131  $   544
                                                      =======  =======  =======
</TABLE>


                     The accompanying notes are an integral
                       part of the financial statements.


<PAGE>   52

                 THE NORTHWESTERN MUTUAL LIFE INSURANCE COMPANY
              NOTES TO CONSOLIDATED STATUTORY FINANCIAL STATEMENTS
                        DECEMBER 31, 1997, 1996 AND 1995



NOTE 1 - PRINCIPAL ACCOUNTING POLICIES

The accompanying consolidated statutory financial statements include the
accounts of The Northwestern Mutual Life Insurance Company ("Company") and its
wholly-owned life insurance subsidiary, Northwestern Long Term Care Insurance
Company ( "Subsidiary").  The Company offers life, annuity and disability
income products to the personal, business, estate and tax-qualified markets.

The consolidated financial statements have been prepared using accounting
policies prescribed or permitted by the Office of the Commissioner of Insurance
of the State of Wisconsin ("statutory basis of accounting").  Prior to December
15, 1995, these policies were considered generally accepted accounting
principles ("GAAP") for mutual life insurance enterprises.  However, in April
1993, the Financial Accounting Standards Board issued Interpretation No. 40,
"Applicability of Generally Accepted Accounting Principles to Mutual Life
Insurance Companies and Other Enterprises," which established a different
definition of GAAP for mutual life insurance enterprises.  Under the
Interpretation, financial statements of mutual life insurance enterprises for
periods beginning after December 15, 1995 which are prepared on the statutory
basis of accounting are no longer characterized as being in conformity with
GAAP.

Financial statements prepared on the statutory basis of accounting vary from
financial statements prepared on a GAAP basis primarily because on a GAAP basis
(1) policy acquisition costs are deferred and amortized, (2) investment
valuations and insurance reserves are based on different assumptions, (3) funds
received under deposit-type contracts are not reported as premium revenue, and
(4) deferred taxes are provided for temporary differences between book and tax
basis of certain assets and liabilities.  The effects on the financial
statements of the differences between the statutory basis of accounting and
GAAP are material to the Company.

The preparation of financial statements in conformity with the statutory basis
of accounting requires management to make estimates and assumptions that affect
the reported amounts of assets and liabilities at the date of the financial
statements and the reported amounts of revenues and expenses during the
reporting period.  Actual future results could differ from these estimates.

Investments

The Company's investments are valued on the following bases:


Bonds                 -      Amortized cost using the interest method;
                             loan-backed and structured securities are 
                             amortized using estimated prepayment rates and,
                             generally, the prospective adjustment method


                                     - 1 -


<PAGE>   53

                 THE NORTHWESTERN MUTUAL LIFE INSURANCE COMPANY
              NOTES TO CONSOLIDATED STATUTORY FINANCIAL STATEMENTS
                        DECEMBER 31, 1997, 1996 AND 1995


Common and preferred stocks     -    Common stocks are carried at market value,
                                     preferred stocks are generally carried at
                                     cost, and unconsolidated subsidiaries are
                                     recorded as equity in subsidiaries' net
                                     assets  
Mortgage loans                  -    Amortized cost
Real estate                     -    Lower of cost, less depreciation and
                                     encumbrances, or estimated net realizable
                                     value  
Policy loans                    -    Unpaid principal balance, which
                                     approximates fair value 
Other investments               -    Consists primarily of joint ventures which
                                     are valued at equity in ventures' net
                                     assets  
Cash and temporary investments  -    Amortized cost, which approximates fair
                                     value 

Cash and Temporary Investments

Temporary investments consist of debt securities that have maturities of one
year or less at acquisition.

Net Investment Income

Net investment income includes interest and dividends received or due and
accrued on debt securities and stocks, equity in unconsolidated subsidiaries'
earnings and the Company's prorated portion of joint venture income. Net
investment income is reduced by investment management expenses, real estate
depreciation and depletion related to energy assets.

Interest Maintenance Reserve

The Company is required to maintain an interest maintenance reserve ("IMR").
The IMR is used to defer realized gains and losses, net of tax, on fixed income
investments resulting from changes in interest rates.  Net realized gains and
losses deferred to the IMR are amortized into investment income over the
approximate remaining term to maturity of the investment sold.

Asset Valuation Reserve

The Company is required to maintain an asset valuation reserve ("AVR"). The
AVR establishes a general reserve for invested assets held by the Company       
using a formula prescribed by state regulations.  The AVR is designed to
stabilize the general contingency reserves against potential declines in the
value of investments.

                                     - 2 -


<PAGE>   54

                 THE NORTHWESTERN MUTUAL LIFE INSURANCE COMPANY
              NOTES TO CONSOLIDATED STATUTORY FINANCIAL STATEMENTS
                        DECEMBER 31, 1997, 1996 AND 1995


Separate Account Business

Separate account assets and related policy liabilities represent the segregation
of funds deposited by "variable" life insurance and annuity policyowners. 
Policyowners bear the investment performance risk associated with variable
products.  Separate account assets are invested at the direction of the
policyowner in a variety of Company-managed mutual funds and/or a fixed interest
rate option.  Separate account assets are reported at fair market value.


Reserves for Policy Benefits

Reserves for policy benefits are determined by actuarial estimates based on
mortality and morbidity experience tables and valuation interest rates
prescribed by the Office of the Commissioner of Insurance of the State of
Wisconsin.  See Note 3.

Premium Revenue and Operating Expenses

Life insurance premiums are recognized as revenue at the beginning of each
policy year.  Annuity and disability income premiums are recognized when
received by the Company. Operating expenses, including costs of acquiring new
policies, are charged to operations as incurred.

Policyowner Dividends

All life insurance policies, and certain annuity and disability income
policies, issued by the Company are participating.  Annually, the Company's
Board of Trustees approves dividends payable on participating policies in the
following fiscal year, which are accrued and charged to operations when
approved.

Reclassification

Certain 1996 and 1995 financial statement balances have been reclassified to
conform to the current year presentation.

NOTE 2 - INVESTMENTS

Debt Securities

Debt securities consist of all bonds and fixed-maturity preferred stocks. The
estimated market values of debt securities are based upon quoted market prices,
if available. For securities not actively traded, fair values are estimated
using independent pricing services or internally developed pricing models.


                                     - 3 -


<PAGE>   55

                 THE NORTHWESTERN MUTUAL LIFE INSURANCE COMPANY
              NOTES TO CONSOLIDATED STATUTORY FINANCIAL STATEMENTS
                        DECEMBER 31, 1997, 1996 AND 1995



Statement value, which principally represents amortized cost, and estimated
market value of the Company's debt securities at December 31, 1997 and 1996 are
as follows:


<TABLE>
<CAPTION>
December 31, 1997                         Reconciliation to Estimated Market Value
- -----------------                      ----------------------------------------------
                                            Gross           Gross        Estimated
                            Statement    Unrealized      Unrealized       Market
                              Value     Appreciation    Depreciation      Value
                            ---------  --------------  --------------  --------------
                                                        (in millions)
<S>                         <C>        <C>             <C>             <C>
US Government and
 political obligations      $   3,695   $         336   $          (3)  $       4,028

Mortgage-backed securities      7,015             264              (4)          7,275

Corporate and other
 debt securities               21,649           1,098            (208)         22,539
                            ---------  --------------  --------------  --------------

                               32,359           1,698            (215)         33,842

Preferred stocks                  167               4              (2)            169
                            ---------  --------------  --------------  --------------

  Total                     $  32,526  $        1,702  $         (217) $       34,011
                            =========  ==============  ==============  ==============

<CAPTION>

December 31, 1996                      Reconciliation to Estimated Market Value
- -----------------                      ----------------------------------------------
                                             Gross           Gross       Estimated
                            Statement     Unrealized      Unrealized       Market
                              Value      Appreciation    Depreciation      Value
                            ---------  --------------  --------------  --------------
                                                        (in millions)
<S>                        <C>         <C>             <C>             <C>
US Government and
 political obligations      $   4,789  $          171  $           (2) $        4,958

Mortgage-backed securities      6,747             179             (38)          6,888

Corporate and other
 debt securities               17,540             776             (99)         18,217
                            ---------  --------------  --------------  --------------

                               29,076           1,126            (139)         30,063

Preferred stocks                   84               6              (1)             89
                            ---------  --------------  --------------  --------------

  Total                     $  29,160  $        1,132  $         (140) $       30,152
                            =========  ==============  ==============  ==============
</TABLE>



                                     - 4 -


<PAGE>   56

                 THE NORTHWESTERN MUTUAL LIFE INSURANCE COMPANY
              NOTES TO CONSOLIDATED STATUTORY FINANCIAL STATEMENTS
                        DECEMBER 31, 1997, 1996 AND 1995



The statement value of debt securities by contractual maturity at December 31,
1997 and 1996 is shown below.  Expected maturities may differ from contractual
maturities because borrowers may have the right to call or prepay obligations
with or without call or prepayment penalties.

                                                December 31,    December 31,
                                                   1997            1996 
                                                ------------   -------------
                                                       (in millions)


        Due in one year or less                   $    605    $     457
                                                                 
        Due after one year through five years        4,878        4,077
                                                                 
        Due after five years through ten years       9,760        7,802
                                                                 
        Due after ten years                         10,268       10,077
                                                  --------    ---------
                                                                 
                                                    25,511       22,413
                                                                 
        Mortgage-backed securities                   7,015        6,747
                                                  --------    ---------
                                                                 
                                                  $ 32,526    $  29,160
                                                  ========    =========


Stocks

The estimated market values of common and perpetual preferred stocks are based
upon quoted market prices, if available. For securities not actively traded,
fair values are estimated using independent pricing services or internally
developed pricing models.

The cost of common and preferred stock held by the Company at December 31, 1997
and 1996 is $5.0 billion and $3.7 billion, respectively.

Mortgage Loans and Real Estate

Mortgage loans are collateralized by properties located throughout the United
States and Canada.  The Company attempts to minimize mortgage loan investment
risk by diversification of geographic locations and types of properties.

The fair value of mortgage loans as of December 31, 1997 and 1996 was
approximately $11.5 billion and $9.8 billion, respectively.  The fair value of
the mortgage loan portfolio is estimated by discounting the future estimated
cash flows using current interest rates of debt securities with similar credit
risk and maturities, or utilizing net realizable values.

                                     - 5 -


<PAGE>   57

                 THE NORTHWESTERN MUTUAL LIFE INSURANCE COMPANY
              NOTES TO CONSOLIDATED STATUTORY FINANCIAL STATEMENTS
                        DECEMBER 31, 1997, 1996 AND 1995



At December 31, 1997, real estate includes $61 million acquired through
foreclosure and $124 million of home office real estate.  In 1997 and 1996, the
Company recorded unrealized losses of $2 million and $43 million, respectively,
for the excess of carrying value over fair value of certain real estate
investments and mortgage loans.

Realized Gains and Losses

Realized investment gains and losses for the years ended December 31, 1997,
1996 and 1995 are as follows:


<TABLE>
<CAPTION>
                           For the year ended              For the year ended            For the year ended
                           December 31, 1997               December 31, 1996             December 31, 1995
                       -----------------------------   ----------------------------  ----------------------------
                                               Net                           Net                           Net
                                            Realized                       Realized                      Realized
                       Realized    Realized   Gains    Realized  Realized   Gains    Realized  Realized   Gains
                         Gains      Losses   (Losses)   Gains     Losses   (Losses)   Gains     Losses   (Losses)
                       ---------  --------- ---------  --------  -------- ---------- --------  -------- ---------
                                                               (In millions)
<S>                    <C>       <C>         <C>      <C>      <C>          <C>       <C>     <C>         <C>
Bonds                  $    518  $  (269)    $  249   $   396  $   (383)    $   13    $  576  $  (130)    $  446
Common and
preferred Stocks            533     (150)       383       580      (115)       465       574     (429)       145
Mortgage loans               14      (14)         -         2       (15)       (13)        2      (32)       (30)
Real estate                 100       (2)        98        36         0         36        14       (3)        11
Other invested
assets                      338     (105)       233       204       (51)       153       188      (95)        93
                        -------  -------     ------   -------   -------     ------    ------  -------     ------

                        $ 1,503  $  (540)    $  963   $ 1,218   $  (564)    $  654    $1,354  $  (689)    $  665
                        =======  =======     ======   =======   =======     ======    ======  =======     ======
Less: Capital
 gains taxes                                    340                            224                           239
Less:  IMR deferrals                            209                             35                           289
                                             ------                         ------                        ------

Net realized
 capital gains                               $  414                         $  395                        $  137
                                             ======                         ======                        ======
</TABLE>


Securities Lending

The Company has entered into a securities lending agreement whereby certain
securities are loaned to third parties, primarily major brokerage firms.  The
Company's policy requires a minimum of 102 percent of the fair value of the
loaned securities as collateral, calculated on a daily basis in the form of
either cash or securities. Collateral assets received and related liability due
to counterparties of $1.5 billion and $1.0 billion are included in the
consolidated statements of financial position at December 31, 1997 and 1996,
respectively, and approximate the statement value of securities loaned at those
dates.

                                     - 6 -


<PAGE>   58

                 THE NORTHWESTERN MUTUAL LIFE INSURANCE COMPANY
              NOTES TO CONSOLIDATED STATUTORY FINANCIAL STATEMENTS
                        DECEMBER 31, 1997, 1996 AND 1995



Investment in MGIC

The Company owns 18.4% (20.9 million shares) of the outstanding common stock of
MGIC Investment Corporation ("MGIC").  This investment is accounted for using
the equity method.  At December 31, 1997, the market value of the Company's
investment in MGIC exceeded the statement value of $273 million by $768
million.

In July 1995, the Company entered into a forward contract with a brokerage firm
to deliver 8.8 million to 10.7 million shares of MGIC (or cash in an amount
equal to the market value of the MGIC shares at contract maturity) in August,
1998, in exchange for a fixed cash payment of $247 million ($24 per share).
The Company's objective in entering into the forward contract was to hedge
against depreciation in the value of its MGIC holdings during the contract
period below the initial spot price of $24, while partially participating in
appreciation, if any, during the forward contract's duration.

Derivative Financial Instruments

In the normal course of business, the Company enters into transactions to
reduce its exposure to fluctuations in interest rates, foreign currency
exchange rates and market volatility. These hedging strategies include the use
of forwards, futures, options and swaps. In addition to the use of derivatives
for hedging purposes, equity swaps were held for investment purposes during
1997.

The Company held the following positions for hedging purposes at December 31,
1997:


<TABLE>
<CAPTION>
                                            Notional
   Derivative Financial Instrument          Amounts               Risks Reduced
- --------------------------------------  ----------------  ----------------------------------------
<S>                                     <C>               <C>
                                            (inmillions)

Foreign Currency Forward Contracts              $564      Currency exposure on foreign-
                                                          denominated investments.
                                                     
Common Stock Futures                             327      Stock market price fluctuation.
                                                     
Bond Futures                                      95      Bond market price fluctuation.
                                                     
Options to acquire Interest Rate Swaps           530      Interest rates payable on
                                                          certain annuity and insurance contracts.

Foreign Currency and Interest Rate Swaps         209      Interest rates on variable rate
                                                          notes and currency exposure on foreign- denominated bonds.

</TABLE>

The notional or contractual amounts of derivative financial instruments are
used to denominate

                                     - 7 -


<PAGE>   59

                 THE NORTHWESTERN MUTUAL LIFE INSURANCE COMPANY
              NOTES TO CONSOLIDATED STATUTORY FINANCIAL STATEMENTS
                        DECEMBER 31, 1997, 1996 AND 1995


these types of transactions and do not represent the amounts exchanged between
the parties.

The notional amount of equity swaps outstanding at December 31, 1997 was $143
million.

The hedges are recorded by the Company in the same manner as the underlying
investments.  Foreign currency forwards, foreign currency swaps, stock futures,
and options to acquire interest rate swaps are reported at market value. There
is no statement value reported for interest rate swaps and bond futures prior
to the settlement of the contract.  Changes in the values of these contracts
are expected to offset gains and losses on the hedged items.  For hedges
reported at market value, gains and losses are unrealized until expiration of
the contract.  The effect of derivative transactions is not material to the
Company's results of operations or financial position.


NOTE 3 - RESERVES FOR POLICY BENEFITS

Life insurance reserves on substantially all policies issued since 1978 are
based on the Commissioner's Reserve Valuation Method ("CRVM") with interest
rates ranging from 3-1/2% to 5-1/2%.  Other life policy reserves are based
primarily on the net level premium method employing various mortality tables at
interest rates ranging from 2% to 4-1/2%.

Deferred annuity reserves on contracts issued since 1985 are valued using CRVM
with interest rates ranging from 3-1/2% to 6-1/4%.  Other deferred annuity
reserves are based on the contract value.  Immediate annuity reserves are based
on present values of expected benefit payments at interest rates ranging from
3-1/2% to 7-1/2%.

Active life reserves for disability income ("DI") policies issued since 1987
are primarily based on the two-year preliminary term method using a 4% interest
rate and the 1985 Commissioner's Individual Disability Table A ("CIDA") for
morbidity.  Active life reserves for prior DI policies are estimated using the
net level premium method, a 3% to 4% interest rate and the 1964 Commissioner's
Disability Table for morbidity.  Disabled life reserves for DI policies are
based on the present values of expected benefit payments using primarily the
1985 CIDA (modified for Company experience in the first two years of
disability) with interest rates ranging from 3% to 5-1/2%.

Use of these actuarial tables and methods involves estimation of future
mortality and morbidity based on past experience.  Actual future experience
could differ from these estimates.



                                     - 8 -


<PAGE>   60

                 THE NORTHWESTERN MUTUAL LIFE INSURANCE COMPANY
              NOTES TO CONSOLIDATED STATUTORY FINANCIAL STATEMENTS
                        DECEMBER 31, 1997, 1996 AND 1995



NOTE 4 - EMPLOYEE AND AGENT BENEFIT PLANS

The Company sponsors noncontributory defined benefit retirement plans for all
eligible employees and agents.  The expense associated with these plans is
generally recorded by the Company in the period contributions to the plans are
funded.  As of January 1, 1997, the most recent actuarial valuation date
available, the defined benefit plans were fully funded.  In addition, the
Company has a contributory 401(k) plan for eligible employees and a
noncontributory defined contribution plan for all full-time agents. The
Company's contributions are expensed in the period contributions are required
under the plan.  The defined benefit and defined contribution plans' assets of
$1.4 billion at December 31, 1997 are primarily invested in the separate
accounts of the Company.

In addition to pension benefits, the Company provides certain health care and
life insurance benefits ("postretirement benefits") for retired employees.
Substantially all employees may become eligible for these benefits if they
reach retirement age while working for the Company.  Postretirement benefit cost
for the year ended December 31, 1997 was a net benefit of $1.3 million; it
includes the expected cost of postretirement benefits for newly eligible and
vested employees, interest cost and return on plan assets totaling $3.6 million,
offset by gains from favorable differences between actuarial assumptions and
actual experience of $4.9 million. 


<TABLE>
<CAPTION>
                                                    December 31,           December 31,   
                                                        1997                  1996        
                                                    ------------           -----------    
   <S>                                              <C>                   <C>             
   Unfunded postretirement benefit obligation                                             
   for retirees and other fully eligible employees  $34 million           $35 million     
   (Accrued in statement of financial position)                                           
                                                                                          
   Estimated postretirement benefit obligation                                            
   for active non-vested employees (Not accrued                                           
   until employee vests)                            $50 million           $43 million     
                                                                                          
   Discount rate                                    7%                    7%              

   Health care cost trend rate                      10% to an ultimate    10% to an ultimate 
                                                    5%, declining 1%      5%, declining 1% 
                                                    for 5 years           for 5 years

</TABLE>

If the health care cost trend rate assumptions were increased by 1%, the
accrued postretirement benefit obligation as of December 31, 1997 would be
increased by $4 million.

At December 31, 1997, the recorded postretirement benefit obligation was
reduced by $20 million for assets funded for postretirement health care
benefits.


                                     - 9 -


<PAGE>   61

                 THE NORTHWESTERN MUTUAL LIFE INSURANCE COMPANY
              NOTES TO CONSOLIDATED STATUTORY FINANCIAL STATEMENTS
                        DECEMBER 31, 1997, 1996 AND 1995



NOTE 5 - REINSURANCE

In the normal course of business, the Company seeks to limit its exposure to
loss on any single insured and to recover a portion of benefits paid by ceding
to reinsurers under excess coverage and co-insurance contracts. The Company
retains a maximum of $15 million of coverage per individual life and $20
million maximum of coverage per joint life. The Company has an excess
reinsurance contract for disability income policies with retention limits
varying based upon on coverage type.

The amounts shown in the accompanying consolidated financial statements are net
of reinsurance activity.  Benefit reserves at December 31, 1997 and 1996 are
reported net of reinsurance of $435 million and $355 million, respectively.
The effect of reinsurance on premiums and benefits for the years ended December
31, 1997, 1996 and 1995 is as follows:

<TABLE>
<CAPTION>
                                                      (in millions)
                                                  1997     1996    1995
                                                 ------  -------  ------
 <S>                                             <C>      <C>     <C>
 Direct premiums                                 $7,647   $7,064  $6,452
 Reinsurance ceded                                 (353)    (397)   (256)
                                                 ------  -------  ------
                                                         
 Net premium revenue                             $7,294   $6,667  $6,196
                                                 ======  =======  ======
                                                         
 Benefits to policyowners and beneficiaries      $8,057   $7,348  $6,818
 Reinsurance recoveries                            (136)    (147)   (142)
                                                 ------  -------  ------
                                                         
 Net benefits to policyowners and beneficiaries  $7,921   $7,201  $6,676
                                                 ======  =======  ======
</TABLE>


In addition, the Company received $115 million, $93 million and $67 million in
1997, 1996 and 1995 respectively, from reinsurers representing reimbursement of
commissions and other expenses.  These amounts are included in other income in
the consolidated statement of operations.

Reinsurance contracts do not relieve the Company from its obligations to
policyholders.  Failure of reinsurers to honor their obligations could result
in losses to the Company; consequently, allowances are established for amounts
deemed uncollectible.  The Company evaluates the financial condition of its
reinsurers and monitors concentrations of credit risk arising from similar
geographic regions, activities, or economic characteristics of the reinsurers
to minimize its exposure to significant losses from reinsurer insolvencies


                                     - 10 -


<PAGE>   62

                 THE NORTHWESTERN MUTUAL LIFE INSURANCE COMPANY
              NOTES TO CONSOLIDATED STATUTORY FINANCIAL STATEMENTS
                        DECEMBER 31, 1997, 1996 AND 1995



NOTE 6 - INCOME TAXES

Provisions for income taxes are based on current income tax payable without
recognition of deferred taxes.  The Company files a consolidated life-nonlife
federal income tax return.  Federal income tax returns for years through 1988
are closed as to further assessment of tax.  Adequate provision has been made
in the financial statements for any additional taxes which may become due with
respect to the open years.

The Company's effective tax rate on gains from operations before income tax
expense (after dividends) in 1997, 1996 and 1995 were 56%, 67% and 60%,
respectively.  The Company's effective tax rate exceeds the federal corporate
rate of 35% because, (1) the Company pays a tax that is assessed only on mutual
life insurance companies which treats a portion of policyholder dividends like
nondeductible dividends paid to shareholders of stock companies ("equity tax"),
and (2) the Company must capitalize and amortize (as opposed to immediately
deducting) an amount deemed to represent the cost of acquiring new business
("DAC tax").


NOTE 7 - CONTINGENCIES

The Company has guaranteed certain obligations of its affiliates.  These
guarantees totaled approximately $112 million at December 31, 1997 and are
generally supported by the underlying net asset values of the affiliates.

The Company is engaged in various legal actions in the normal course of its
investment and insurance operations.  In the opinion of management, any losses
resulting from such actions would not have a material effect on the Company's
financial condition.


Doc. No. 79585

                                     - 11 -


<PAGE>   63




                 The Northwestern Mutual Life Insurance Company
                                   Form 10-K



                                   EXHIBIT I

Reference is made to a form of deferred compensation agreement filed as Exhibit
B-2 with Form 10-K for 1970 and The Northwestern Mutual Employee Savings Plan
filed as Exhibit II for 1985.  Pursuant to such contracts the following amounts
were deferred in 1997:


Executive Officers
- ------------------
James D. Ericson            $  224,500
Robert E. Carlson               81,500
Walt J. Wojcik                 202,000
Mason G. Ross                   18,300
Frederic H. Sweet               15,780
James F. Reiskytl               16,700
Richard L. Hall                 27,950
Gary E. Long                    57,500
Donald L. Mellish               46,800
Deborah A. Beck                 33,500
Edward J. Zore                  33,500
Dennis Tamcsin                  71,500
Peter W. Bruce                  58,220
Mark G. Doll                    57,500
John M. Bremer                  45,500
James W. Ehrenstrom             60,500
William C. Koenig               15,000
Leonard F. Stecklein            14,100
Martha M. Valerio              111,830
W. Ward White                   32,508
Barbara F. Piehler              38,500
Thomas E. Dyer                  31,900
Steven T. Catlett               11,856
Gregory C. Oberland              9,500
Susan A. Lueger                 41,760
Meridee J. Maynard              47,200
William H. Beckley              19,100
Robert J. Berdan                17,300
Bruce L. Miller                 24,500
John E. Schlifske               13,520

Trustees
- --------
Stephen F. Keller               45,750
R. Quintus Anderson #2          51,250
Jake E. Gallegos #2             45,750
Patricia Albjerg Graham #2      46,750
Robert C. Buchanan              42,150
Edward E. Barr                  46,750
Sherwood H. Smith, Jr.          50,250
John J. Stollenwerk             83,650
Herman M. Sizemore              45,750
George A. Dickerman             43,250
John E. Steuri                  50,250
Barbara A. King                 28,000

                            $2,059,374
                            ==========


                                                                        

<PAGE>   64

                 The Northwestern Mutual Life Insurance Company
                                   Form 10-K



                                   SIGNATURES

Pursuant to the requirements of Section 13 or 15 (d) of the Securities Exchange
Act of 1934, the registrant has duly caused this report to be signed on its
behalf by the undersigned, thereunto duly authorized.


                                           THE NORTHWESTERN MUTUAL LIFE
                                                 INSURANCE COMPANY
                                                   (Registrant)

                              By   James D. Ericson
                                   -------------------------------------
                                   James D. Ericson
                                   President and Chief Executive Officer


                              By   Gary E. Long
                                   -------------------------------------
                                   Gary E. Long
                                  Vice President and Controller


Date:  March 23, 1998


Pursuant to the requirements of the Securities Exchange Act of 1934, this
report has been signed below by the following persons on behalf of the
registrant and in the capacities and on the dates indicated.


                                 Title

James D. Ericson                 Trustee, President and Chief Executive Officer
- -----------------------
James D. Ericson


                                                            Dated March 23, 1998
                                                                        
                                                                        
<PAGE>   65

                 The Northwestern Mutual Life Insurance Company
                                   Form 10-K



                             SIGNATURES (continued)


R.   QUINTUS ANDERSON*                          Trustee
- -------------------------------
R.   Quintus Anderson


EDWARD E. BARR*                                 Trustee
- -------------------------------
Edward E. Barr


GORDON T. BEAHAM, III*                          Trustee
- -------------------------------
Gordon T. Beaham, III


ROBERT C. BUCHANAN*                             Trustee
- -------------------------------
Robert C. Buchanan


ROBERT E. CARLSON*                              Trustee
- -------------------------------
Robert E. Carlson


GEORGE A. DICKERMAN*                            Trustee
- -------------------------------
George A. Dickerman


PIERRE S. DU PONT*                              Trustee     Dated March 23, 1998
- -------------------------------
Pierre S. Du Pont


J.   E. GALLEGOS*                               Trustee
- -------------------------------
J.   E. Gallegos


STEPHEN N. GRAFF*                               Trustee
- -------------------------------
Stephen N. Graff


PATRICIA ALBJERG GRAHAM*                        Trustee
- -------------------------------
Patricia Alberg Graham





<PAGE>   66

                 The Northwestern Mutual Life Insurance Company
                                   Form 10-K



                             SIGNATURES (continued)



STEPHEN F. KELLER*                      Trustee
- -------------------------------------
Stephen F. Keller


BARBARA A. KING*                        Trustee
- -------------------------------------
Barbara A. King


J. THOMAS LEWIS*                        Trustee
- -------------------------------------
J. Thomas Lewis

DANIEL F. McKEITHAN, JR.*               Trustee
- -------------------------------------
Daniel F. McKeithan, Jr.

                                
GUY A. OSBORN*                          Trustee
- -------------------------------------
Guy A. Osborn


TIMOTHY D. PROCTOR*                     Trustee
- -------------------------------------
Timothy D. Proctor


DONALD J. SCHUENKE*                     Trustee         Dated March 23, 1998
- -------------------------------------
Donald J. Schuenke


H. MASON SIZEMORE, JR.*                 Trustee
- -------------------------------------
H. Mason Sizemore, Jr.

HAROLD B. SMITH*                        Trustee
- -------------------------------------
Harold B. Smith


SHERWOOD H. SMITH, JR.*                 Trustee
- -------------------------------------
Sherwood H. Smith, Jr.


JOHN E. STEURI*                         Trustee
- -------------------------------------
John E. Steuri


JOHN J. STOLLENWERK*                    Trustee
- -------------------------------------
John J. Stollenwerk


BARRY L. WILLIAMS*                      Trustee
- -------------------------------------
Barry L. Williams


KATHRYN D. WRISTON*                     Trustee
- -------------------------------------
Kathryn D. Wriston


*By JAMES D. ERICSON*
    ---------------------------------
    James D. Ericson, Attorney in
    fact, pursuant to the Power of
    Attorney attached hereto




<PAGE>   67

                 The Northwestern Mutual Life Insurance Company
                                   Form 10-K



                               POWER OF ATTORNEY

     The undersigned Trustees of THE NORTHWESTERN MUTUAL LIFE INSURANCE COMPANY
hereby constitute and appoint James D. Ericson and Robert E. Carlson, or either
of them, their true and lawful attorneys and agents to sign the names of the
undersigned Trustees to (1) the registration statement or statements to be
filed under the Securities Act of 1933 and to any instrument or document filed
as part thereof or in connection therewith or in any way related thereto, and
any and all amendments thereto in connection with variable contracts issued or
sold by The Northwestern Mutual Life Insurance Company or any separate account
credited therein and (2) the Form 10-K Annual Report or Reports of The
Northwestern Mutual Life Insurance Company and/or its separate accounts for its
or their fiscal year ended December 31, 1998 to be filed as part thereof or in
connection therewith or in any way related thereto, and any and all amendments
thereto.  "Variable contracts" as used herein means any contracts providing for
benefits or values which may vary according to the investment experience of any
separate account maintained by The Northwestern Mutual Life Insurance Company,
including variable annuity contracts and variable life insurance policies.
Each of the undersigned hereby ratifies and confirms all that said attorneys
and agents shall do or cause to be done by virtue hereof.

     IN WITNESS WHEREOF, each of the undersigned has subscribed these presents
this 23rd day of July, 1997.



                         R. QUINTUS ANDERSON           Trustee      
                         ------------------------------                      
                         R. Quintus Anderson                        
                                                                    
                                                                    
                         EDWARD E. BARR                Trustee      
                         ------------------------------                      
                         Edward E. Barr                             
                                                                    
                                                                    
                         GORDON T. BEAHAM, III         Trustee      
                         ------------------------------                      
                         Gordon T. Beaham, III                      
                                                                    
                                                                    
                         ROBERT C. BUCHANAN            Trustee      
                         ------------------------------                      
                         Robert C. Buchanan                         
                                                                    
                                                                    
                         ROBERT E. CARLSON             Trustee      
                         ------------------------------                      
                         Robert E. Carlson                          
                                                                    
                                                                    
                         GEORGE A. DICKERMAN           Trustee      
                         ------------------------------                      
                         George A. Dickerman                        
                                                                    
                                                                    
                         PIERRE S. DU PONT             Trustee      
                         ------------------------------                      
                         Pierre S. Du Pont                          
                                                                    
                                                                    
                         JAMES D. ERICSON              Trustee      
                         ------------------------------                      
                         James D. Ericson                           
                                                                    
                         J. E. GALLEGOS                Trustee      
                         ------------------------------                      
                         J. E. Gallegos                             
                                                                    
                                                                    
                         STEPHEN N. GRAFF              Trustee      
                         ------------------------------                      
                         Stephen N. Graff                           
                                                                    
                                                                    
                         PATRICIA ALBJERG GRAHAM        Trustee     
                         ------------------------------                      
                         Patricia Albjerg Graham                    






<PAGE>   68

                 The Northwestern Mutual Life Insurance Company
                                   Form 10-K


                        STEPHEN F. KELLER             Trustee
                        ------------------------------                      
                        Stephen F. Keller


                        BARBARA A. KING               Trustee
                        ------------------------------                      
                        Barbara A. King



                        J. THOMAS LEWIS               Trustee
                        ------------------------------                      
                        J. Thomas Lewis



                        DANIEL F. McKEITHAN, JR.      Trustee
                        ------------------------------                      
                        Daniel F. McKeithan, Jr.


                        GUY A. OSBORN                 Trustee
                        ------------------------------                      
                        Guy A. Osborn


                        TIMOTHY D. PROCTOR            Trustee
                        ------------------------------                      
                        Timothy D. Proctor


                        DONALD J. SCHUENKE            Trustee
                        ------------------------------                      
                        Donald J. Schuenke



                        H. MASON SIZEMORE, JR.        Trustee
                        ------------------------------                      
                        H. Mason Sizemore, Jr.



                        HAROLD B. SMITH               Trustee
                        ------------------------------                      
                        Harold B. Smith


                        SHERWOOD H. SMITH, JR.        Trustee
                        ------------------------------                      
                        Sherwood H. Smith, Jr.


                        JOHN E. STEURI                Trustee
                        ------------------------------                      
                        John E. Steuri


                        JOHN J. STOLLENWERK           Trustee
                        ------------------------------                      
                        John J. Stollenwerk


                        BARRY L. WILLIAMS             Trustee
                        ------------------------------                      
                        Barry L. Williams


                        KATHRYN D. WRISTON            Trustee
                        ------------------------------                      
                        Kathryn D. Wriston










WARNING: THE EDGAR SYSTEM ENCOUNTERED ERROR(S) WHILE PROCESSING THIS SCHEDULE.

<TABLE> <S> <C>

<ARTICLE> 6
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM NORTHWESTERN
MUTUAL VARIABLE LIFE ACCOUNT, DECEMBER 31, 1997 FINANCIAL STATEMENTS AND IS
QUALIFIED IN ITS ENTIRETY BY REFERENCE TO SUCH POST-EFFECTIVE AMENDMENT.
</LEGEND>
<MULTIPLIER> 1000
       
<S>                             <C>
<PERIOD-TYPE>                   YEAR
<FISCAL-YEAR-END>                          DEC-31-1997
<PERIOD-START>                             JAN-01-1997
<PERIOD-END>                               DEC-31-1997
<INVESTMENTS-AT-COST>                          468,890
<INVESTMENTS-AT-VALUE>                         649,887
<RECEIVABLES>                                    1,878
<ASSETS-OTHER>                                       0
<OTHER-ITEMS-ASSETS>                                 0
<TOTAL-ASSETS>                                 651,765
<PAYABLE-FOR-SECURITIES>                             0
<SENIOR-LONG-TERM-DEBT>                              0
<OTHER-ITEMS-LIABILITIES>                        3,370
<TOTAL-LIABILITIES>                              3,370
<SENIOR-EQUITY>                                648,395
<PAID-IN-CAPITAL-COMMON>                             0
<SHARES-COMMON-STOCK>                                0
<SHARES-COMMON-PRIOR>                                0
<ACCUMULATED-NII-CURRENT>                            0
<OVERDISTRIBUTION-NII>                               0
<ACCUMULATED-NET-GAINS>                              0
<OVERDISTRIBUTION-GAINS>                             0
<ACCUM-APPREC-OR-DEPREC>                             0
<NET-ASSETS>                                   348,395
<DIVIDEND-INCOME>                               33,253
<INTEREST-INCOME>                                    0
<OTHER-INCOME>                                       0
<EXPENSES-NET>                                   7,047
<NET-INVESTMENT-INCOME>                         26,206
<REALIZED-GAINS-CURRENT>                        23,135
<APPREC-INCREASE-CURRENT>                       56,364
<NET-CHANGE-FROM-OPS>                          105,705
<EQUALIZATION>                                       0
<DISTRIBUTIONS-OF-INCOME>                            0
<DISTRIBUTIONS-OF-GAINS>                             0
<DISTRIBUTIONS-OTHER>                                0
<NUMBER-OF-SHARES-SOLD>                              0
<NUMBER-OF-SHARES-REDEEMED>                          0
<SHARES-REINVESTED>                                  0
<NET-CHANGE-IN-ASSETS>                               0
<ACCUMULATED-NII-PRIOR>                              0
<ACCUMULATED-GAINS-PRIOR>                            0
<OVERDISTRIB-NII-PRIOR>                              0
<OVERDIST-NET-GAINS-PRIOR>                           0
<GROSS-ADVISORY-FEES>                                0
<INTEREST-EXPENSE>                                   0
<GROSS-EXPENSE>                                      0
<AVERAGE-NET-ASSETS>                                 0
<PER-SHARE-NAV-BEGIN>                                0
<PER-SHARE-NII>                                      0
<PER-SHARE-GAIN-APPREC>                              0
<PER-SHARE-DIVIDEND>                                 0
<PER-SHARE-DISTRIBUTIONS>                            0
<RETURNS-OF-CAPITAL>                                 0
<PER-SHARE-NAV-END>                                  0
<EXPENSE-RATIO>                                      0
<AVG-DEBT-OUTSTANDING>                               0
<AVG-DEBT-PER-SHARE>                                 0
        

</TABLE>

<TABLE> <S> <C>

<ARTICLE> 6
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM NORTHWESTERN
MUTUAL VARIABLE LIFE ACCOUNT, DECEMBER 31, 1997 FINANCIAL STATEMENTS AND IS
QUALIFIED IN ITS ENTIRETY BY REFERENCE TO SUCH POST-EFFECTIVE AMENDMENT.
</LEGEND>
<MULTIPLIER> 1000
       
<S>                             <C>
<PERIOD-TYPE>                   YEAR
<FISCAL-YEAR-END>                          DEC-31-1997
<PERIOD-START>                             JAN-01-1997
<PERIOD-END>                               DEC-31-1997
<INVESTMENTS-AT-COST>                          381,997
<INVESTMENTS-AT-VALUE>                         493,768
<RECEIVABLES>                                    1,387
<ASSETS-OTHER>                                       0
<OTHER-ITEMS-ASSETS>                                 0
<TOTAL-ASSETS>                                 495,155
<PAYABLE-FOR-SECURITIES>                             0
<SENIOR-LONG-TERM-DEBT>                              0
<OTHER-ITEMS-LIABILITIES>                        1,387
<TOTAL-LIABILITIES>                               1387
<SENIOR-EQUITY>                                493,768
<PAID-IN-CAPITAL-COMMON>                             0
<SHARES-COMMON-STOCK>                                0
<SHARES-COMMON-PRIOR>                                0
<ACCUMULATED-NII-CURRENT>                            0
<OVERDISTRIBUTION-NII>                               0
<ACCUMULATED-NET-GAINS>                              0
<OVERDISTRIBUTION-GAINS>                             0
<ACCUM-APPREC-OR-DEPREC>                             0
<NET-ASSETS>                                   493,768
<DIVIDEND-INCOME>                               20,337
<INTEREST-INCOME>                                    0
<OTHER-INCOME>                                       0
<EXPENSES-NET>                                   1,119
<NET-INVESTMENT-INCOME>                         19,218
<REALIZED-GAINS-CURRENT>                         9,097
<APPREC-INCREASE-CURRENT>                       24,920
<NET-CHANGE-FROM-OPS>                           53,235
<EQUALIZATION>                                       0
<DISTRIBUTIONS-OF-INCOME>                            0
<DISTRIBUTIONS-OF-GAINS>                             0
<DISTRIBUTIONS-OTHER>                                0
<NUMBER-OF-SHARES-SOLD>                              0
<NUMBER-OF-SHARES-REDEEMED>                          0
<SHARES-REINVESTED>                                  0
<NET-CHANGE-IN-ASSETS>                               0
<ACCUMULATED-NII-PRIOR>                              0
<ACCUMULATED-GAINS-PRIOR>                            0
<OVERDISTRIB-NII-PRIOR>                              0
<OVERDIST-NET-GAINS-PRIOR>                           0
<GROSS-ADVISORY-FEES>                                0
<INTEREST-EXPENSE>                                   0
<GROSS-EXPENSE>                                      0
<AVERAGE-NET-ASSETS>                                 0
<PER-SHARE-NAV-BEGIN>                                0
<PER-SHARE-NII>                                      0
<PER-SHARE-GAIN-APPREC>                              0
<PER-SHARE-DIVIDEND>                                 0
<PER-SHARE-DISTRIBUTIONS>                            0
<RETURNS-OF-CAPITAL>                                 0
<PER-SHARE-NAV-END>                                  0
<EXPENSE-RATIO>                                      0
<AVG-DEBT-OUTSTANDING>                               0
<AVG-DEBT-PER-SHARE>                                 0
        

</TABLE>


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