MUNICIPAL INVT TR FD INSURED SERIES 303 DEFINED ASSET FUNDS
497, 2000-05-26
Previous: MUNICIPAL INVT TR FD INSURED SERIES 231 DEFINED ASSET FUNDS, 497, 2000-05-26
Next: ASSET INVESTORS CORP, SC 13E3/A, 2000-05-26




                           DEFINED ASSET FUNDS--REGISTERED TRADEMARK--
                           ----------------------------------------------------

                           MUNICIPAL INVESTMENT TRUST FUND
                           INSURED SERIES--303
                           (A UNIT INVESTMENT TRUST)
                           -  PORTFOLIO OF INSURED LONG TERM MUNICIPAL BONDS
                           -  DESIGNED TO BE FREE OF REGULAR FEDERAL INCOME TAX
                           -  MONTHLY INCOME DISTRIBUTIONS

SPONSORS:
MERRILL LYNCH,
PIERCE, FENNER & SMITH
INCORPORATED               -----------------------------------------------------
SALOMON SMITH BARNEY INC.  The Securities and Exchange Commission has not
PRUDENTIAL SECURITIES      approved or disapproved these Securities or passed
INCORPORATED               upon the adequacy of this prospectus. Any
PAINEWEBBER INCORPORATED   representation to the contrary is a criminal offense.
DEAN WITTER REYNOLDS INC.  Prospectus dated May 26, 2000.

<PAGE>
- --------------------------------------------------------------------------------

Defined Asset Funds--Registered Trademark--
Defined Asset Funds-Registered Trademark- is America's oldest and largest family
of unit investment trusts, with over $160 billion sponsored over the last 28
years. Defined Asset Funds has been a leader in unit investment trust research
and product innovation. Our family of Funds helps investors work toward their
financial goals with a full range of quality investments, including municipal,
corporate and government bond portfolios, as well as domestic and international
equity portfolios.

Defined Asset Funds offer a number of advantages:
  - A disciplined strategy of buying and holding with a long-term view is the
    cornerstone of Defined Asset Funds.
  - Fixed portfolio: Defined Funds follow a buy and hold investment strategy;
    funds are not managed and portfolio changes are limited.
  - Defined Portfolios: We choose the stocks and bonds in advance, so you know
    what you're investing in.
  - Professional research: Our dedicated research team seeks out stocks or bonds
    appropriate for a particular fund's objectives.
  - Ongoing supervision: We monitor each portfolio on an ongoing basis.
No matter what your investment goals, tolerance for risk or time horizon,
there's probably a Defined Asset Fund that suits your investment style. Your
financial professional can help you select a Defined Asset Fund that works best
for your investment portfolio.

THE FINANCIAL INFORMATION IN THIS PROSPECTUS IS AS OF THE EVALUATION DATE,
FEBRUARY 29, 2000.

<TABLE>
<S>                                    <C>
CONTENTS
                                       PAGE
                                       ----
Risk/Return Summary..................     3
What You Can Expect From Your
  Investment.........................     7
  Monthly Income.....................     7
  Return Figures.....................     7
  Records and Reports................     7
The Risks You Face...................     8
  Interest Rate Risk.................     8
  Call Risk..........................     8
  Reduced Diversification Risk.......     8
  Liquidity Risk.....................     8
  Concentration Risk.................     8
  Bond Quality Risk..................     8
  Insurance Related Risk.............     8
  Litigation and Legislation Risks...     9
Selling or Exchanging Units..........     9
  Sponsors' Secondary Market.........     9
  Selling Units to the Trustee.......     9
  Exchange Option....................    10
How The Fund Works...................    10
  Pricing............................    10
  Evaluations........................    10
  Income.............................    11
  Expenses...........................    11
  Portfolio Changes..................    11
  Fund Termination...................    12
  Certificates.......................    12
  Trust Indenture....................    12
  Legal Opinion......................    13
  Auditors...........................    13
  Sponsors...........................    13
  Trustee............................    14
  Underwriters' and Sponsors'
    Profits..........................    14
  Public Distribution................    14
  Code of Ethics.....................    14
  Year 2000 Issues...................    14
Taxes................................    14
Supplemental Information.............    16
Financial Statements.................   D-1
</TABLE>

                                       2
<PAGE>
- --------------------------------------------------------------------------------

RISK/RETURN SUMMARY

<TABLE>
<C>  <S>
 1.  WHAT IS THE FUND'S OBJECTIVE?
     The Fund seeks interest income that is
     exempt from regular federal income taxes
     by investing in a fixed portfolio
     consisting primarily of insured
     municipal revenue bonds.

 2.  WHAT ARE MUNICIPAL REVENUE BONDS?
     Municipal revenue bonds are bonds issued
     by states, municipalities and public
     authorities to finance the cost of
     buying, building or improving various
     projects intended to generate revenue,
     such as airports, health care
     facilities, housing and municipal
     electric, water and sewer utilities.
     Generally, payments on these bonds
     depend solely on the revenues generated
     by the projects, excise taxes or state
     appropriations, and are not backed by
     the government's taxing power.

 3.  WHAT IS THE FUND'S INVESTMENT STRATEGY?

  -  The Fund plans to hold to maturity 13
     insured long-term tax-exempt municipal
     bonds with a current aggregate face
     amount of $8,585,000.

  -  The Fund is a unit investment trust
     which means that, unlike a mutual fund,
     the Fund's portfolio is not managed.
  -  The bonds are rated AAA or Aaa by
     Standard & Poor's, Moody's or Fitch.
  -  The Fund is concentrated in refunded
     bonds.
  -  Many of the bonds can be called at a
     premium declining over time to par
     value. Some bonds may be called earlier
     at par for extraordinary reasons.
  -  100% of the bonds are insured by
     insurance companies. Insurance
     guarantees timely payments of principal
     and interest on the bonds (but not Fund
     units or the market value of the bonds
     before they mature).

     The Portfolio consists of municipal
     bonds of the following types:
</TABLE>

<TABLE>
  -  Airports/Ports/Highways                  12%
<C>  <S>
  -  Housing                                  12%
  -  Municipal Water/Sewer Utilities          12%
  -  Refunded Bonds                          26%
  -  Special Tax                              21%
  -  Universities/Colleges                    17%
</TABLE>

<TABLE>
<C>  <S>
 4.  WHAT ARE THE SIGNIFICANT RISKS?

     YOU CAN LOSE MONEY BY INVESTING IN THE
     FUND. THIS CAN HAPPEN FOR VARIOUS
     REASONS, INCLUDING:
  -  Rising interest rates, an issuer's
     worsening financial condition or a drop
     in bond ratings can reduce the price of
     your units.
  -  Assuming no changes in interest rates,
     when you sell your units, they will
     generally be worth less than your cost
     because your cost included a sales fee.
  -  The Fund will receive early returns of
     principal if bonds are called or sold
     before they mature. If this happens your
     income will decline and you may not be
     able to reinvest the money you receive
     at as high a yield or as long a
     maturity.
</TABLE>

<TABLE>
<C>  <S>
 5.  IS THIS FUND APPROPRIATE FOR YOU?

     Yes, if you want monthly income free
     from regular federal income tax. You
     will benefit from a professionally
     selected and supervised portfolio whose
     risk is reduced by investing in bonds of
     several different issuers.
     The Fund is NOT appropriate for you if
     you want a speculative investment that
     changes to take advantage of market
     movements, if you do not want a
     tax-advantaged investment or if you
     cannot tolerate any risk.
</TABLE>

                                       3
<PAGE>

<TABLE>
<C>  <S>
     DEFINING YOUR INCOME
</TABLE>

<TABLE>
<C>  <S>                                           <C>
     WHAT YOU MAY EXPECT (PAYABLE ON THE 25TH DAY
     OF EACH MONTH):
     Regular Monthly Income per unit                $ 4.47
     Annual Income per unit                         $53.74
     RECORD DAY: 10th day of each month

     THESE FIGURES ARE ESTIMATES ON THE EVALUATION DATE;
     ACTUAL PAYMENTS MAY VARY.
</TABLE>

<TABLE>
<C>  <S>
 6.  WHAT ARE THE FUND'S FEES AND EXPENSES?

     This table shows the costs and expenses you may pay,
     directly or indirectly, when you invest in the Fund.

     INVESTOR FEES

     Maximum Sales Fee (Load) on new
     purchases (as a percentage of
     $1,000 invested)                            2.90%

     Employees of some of the Sponsors and their affiliates
     may be charged a reduced sales fee of no less than
     $5.00 per unit.

     The maximum sales fee is reduced if you invest at
     least $100,000, as follows:
</TABLE>

<TABLE>
<CAPTION>
                               YOUR MAXIMUM
                                SALES FEE
          IF YOU INVEST:         WILL BE:
          --------------       ------------
<C>  <S>                       <C>
     Less than $100,000            2.90%
     $100,000 to $249,999          2.65%
     $250,000 to $499,999          2.40%
     $500,000 to $999,999          2.15%
     $1,000,000 and over           1.90%

     Maximum Exchange Fee          1.90%
</TABLE>

<TABLE>
<C>  <S>
     ESTIMATED ANNUAL FUND OPERATING EXPENSES
</TABLE>

<TABLE>
<CAPTION>
                                                    AMOUNT
                                                   PER UNIT
                                                   --------
<C>  <S>                                          <C>
                                                    $ 0.70
     Trustee's Fee
                                                    $ 0.55
     Portfolio Supervision,
     Bookkeeping and
     Administrative Fees
     (including updating
     expenses)
                                                    $ 0.20
     Organization Costs
                                                    $ 0.14
     Evaluator's Fee
                                                    $ 0.24
     Other Operating Expenses
                                                    ------
                                                    $ 1.83
     TOTAL
</TABLE>

<TABLE>
<C>  <S>
     The Sponsors historically paid organization
     costs and updating expenses.
</TABLE>

<TABLE>
<C>  <S>
 7.  HOW HAVE SIMILAR FUNDS PERFORMED IN THE
     PAST?

     IN THE FOLLOWING CHART WE SHOW PAST
     PERFORMANCE OF PRIOR MUNICIPAL INSURED
     SERIES, WHICH HAD THE SAME INVESTMENT
     OBJECTIVES, STRATEGIES AND TYPES OF
     BONDS AS THIS FUND. These prior Insured
     Series were offered after 1987 and were
     outstanding on March 31, 2000. OF
     COURSE, PAST PERFORMANCE OF PRIOR SERIES
     IS NO GUARANTEE OF FUTURE RESULTS OF
     THIS FUND.

     AVERAGE ANNUAL COMPOUND TOTAL RETURNS
     FOR PRIOR SERIES
     REFLECTING ALL EXPENSES. FOR PERIODS
     ENDED 3/31/00.
</TABLE>

 -------------------------------------------------------------------

<TABLE>
 High                    4.66%     5.52%     6.04%      4.85     6.71%     6.63%
 <S>                    <C>       <C>       <C>       <C>       <C>       <C>
 Average                 -2.09      4.45      5.70     -0.05      5.53      6.28
 Low                     -8.22      2.83      5.34     -5.16      3.77      5.93
</TABLE>

 -----------------------------------------------------------

<TABLE>
 <S>                    <C>       <C>       <C>       <C>       <C>       <C>
 Average
 Sales fee               2.11%     5.35%     5.72%
</TABLE>

 -----------------------------------------------------

NOTE: ALL RETURNS REPRESENT CHANGES IN UNIT PRICE WITH DISTRIBUTIONS REINVESTED
 INTO THE MUNICIPAL FUND INVESTMENT ACCUMULATION PROGRAM.

<TABLE>
<C>  <S>
 8.  IS THE FUND MANAGED?

     Unlike a mutual fund, the Fund is not managed
     and bonds are not sold because of market
     changes. Rather, experienced
</TABLE>

<TABLE>
<C>  <S>
     Defined Asset Funds financial analysts
     regularly review the bonds in the Fund.
     The Fund may sell a bond if certain
     adverse credit or other conditions
     exist.
 9.  HOW DO I BUY UNITS?

     The minimum investment is one unit.

     You can buy units from any of the
     Sponsors and other broker-dealers. The
     Sponsors are listed later in this
     prospectus. Some banks may offer units
     for sale through special arrangements
     with the Sponsors, although certain
     legal restrictions may apply.
</TABLE>

                                       4
<PAGE>

<TABLE>
<C>  <S>
     UNIT PRICE PER UNIT              $991.88
     (as of February 29, 2000)

     Unit price is based on the net asset
     value of the Fund plus the sales fee. An
     amount equal to any principal cash, as
     well as net accrued but undistributed
     interest on the unit, is added to the
     unit price. An independent evaluator
     prices the bonds at 3:30 p.m. Eastern
     time every business day. Unit price
     changes every day with changes in the
     prices of the bonds in the Fund.

10.  HOW DO I SELL UNITS?

     You may sell your units at any time to
     any Sponsor or the Trustee for the net
     asset value determined at the close of
     business on the date of sale. You will
     not pay any other fee when you sell your
     units.

11.  HOW ARE DISTRIBUTIONS MADE AND TAXED?

     The Fund pays income monthly. In the
     opinion of bond counsel when each bond
     was issued, interest on the bonds in
     this Fund is generally 100% exempt from
     regular federal income tax.
     A portion of the income may also be
     exempt from state and local personal
     income taxes, depending on where you
     live.

     You will also receive principal payments
     if bonds are sold or called or mature,
     when the cash available is more than
     $5.00 per unit. You will be subject to
     tax on any gain realized by the Fund on
     the disposition of bonds.

12.  WHAT OTHER SERVICES ARE AVAILABLE?

     REINVESTMENT
     You will receive your monthly income in
     cash unless you choose to compound your
     income by reinvesting with no sales fee
     in the Municipal Fund Investment
     Accumulation Program, Inc. This program
     is an open-end mutual fund with a
     comparable investment objective, but
     those bonds generally will not be
     insured. Income from this program will
     generally be subject to state and local
     income taxes. FOR MORE COMPLETE
     INFORMATION ABOUT THE PROGRAM, INCLUDING
     CHARGES AND FEES, ASK THE TRUSTEE FOR
     THE PROGRAM'S PROSPECTUS. READ IT
     CAREFULLY BEFORE YOU INVEST. THE TRUSTEE
     MUST RECEIVE YOUR WRITTEN ELECTION TO
     REINVEST AT LEAST 10 DAYS BEFORE THE
     RECORD DAY OF AN INCOME PAYMENT.

     EXCHANGE PRIVILEGES
     You may exchange units of this Fund for
     units of certain other Defined Asset
     Funds. You may also exchange into this
     Fund from certain other funds. We charge
     a reduced sales fee on exchanges.
</TABLE>

                                       5
<PAGE>
- --------------------------------------------------------------------------------
    TAX-FREE VS. TAXABLE INCOME: A COMPARISON OF TAXABLE AND TAX-FREE YIELDS

<TABLE>
                                      EFFECTIVE
TAXABLE INCOME 2000*                  % TAX                                  TAX-FREE YIELD OF
  SINGLE RETURN      JOINT RETURN     BRACKET      3%        3.5%        4%        4.5%        5%        5.5%        6%
                                                                    IS EQUIVALENT TO A TAXABLE YIELD OF
<S>                <C>                <C>        <C>        <C>        <C>        <C>        <C>        <C>        <C>
- ---------------------------------------------------------------------------------------------------------------------------
$      0- 26,250   $      0- 43,850    15.00       3.53       4.12       4.71       5.29       5.88       6.47       7.06
- ---------------------------------------------------------------------------------------------------------------------------
$ 26,251- 63,550   $ 43,851-105,950    28.00       4.17       4.86       5.56       6.25       6.94       7.64       8.33
- ---------------------------------------------------------------------------------------------------------------------------
$ 63,551-132,600   $105,951-161,450    31.00       4.35       5.07       5.80       6.52       7.25       7.97       8.70
- ---------------------------------------------------------------------------------------------------------------------------
<S>                <C>                <C>        <C>        <C>        <C>        <C>        <C>        <C>        <C>
$132,601-288,350   $161,451-288,350    36.00       4.69       5.47       6.25       7.03       7.81       8.59       9.38
- ---------------------------------------------------------------------------------------------------------------------------
<S>                <C>                <C>        <C>        <C>        <C>        <C>        <C>        <C>        <C>
  OVER $288,350    OVER $288,350       39.60       4.97       5.79       6.62       7.45       8.28       9.11       9.93
- ---------------------------------------------------------------------------------------------------------------------------
<S>                <C>                <C>        <C>        <C>        <C>        <C>        <C>        <C>        <C>

<S>                <C>
TAXABLE INCOME 20
  SINGLE RETURN     6.5%
                      IS
                   EQUIVALENT
                     TO A
                   TAXABLE
                   YIELD OF
- -----------------
$      0- 26,250     7.65
- -----------------
$ 26,251- 63,550     9.03
- -----------------
$ 63,551-132,600     9.42
                   --------
- -----------------
$132,601-288,350    10.16
                   --------
- -----------------
  OVER $288,350     10.76
                   --------
- -----------------
</TABLE>

To compare the yield of a taxable security with the yield of a federally
tax-free security, find your taxable income and read across. The table
incorporates 2000 federal income tax rates and assumes that all income would
otherwise be taxed at a U.S. investor's highest tax rate. Yield figures are for
example only.

*Based upon net amount subject to federal income tax after deductions and
exemptions. This table does not reflect the possible effect of other tax
factors, such as alternative minimum tax, personal exemptions, the phase-out of
exemptions, itemized deductions, the possible partial disallowance of deductions
or state and local taxation. Consequently, investors are urged to consult their
own tax advisers in this regard.

                                       6
<PAGE>
WHAT YOU CAN EXPECT FROM YOUR INVESTMENT

MONTHLY INCOME

The Fund will pay you regular monthly income. Your monthly income may vary
because of:
  - elimination of one or more bonds from the Fund's portfolio because of calls,
    redemptions or sales;
  - a change in the Fund's expenses; or
  - the failure by a bond's issuer to pay interest.

Changes in interest rates generally will not affect your monthly income because
the portfolio is fixed.

Along with your monthly income, you will receive your share of any available
bond principal.

RETURN FIGURES

We cannot predict your actual return, which will vary with unit price, how long
you hold your investment and changes in the portfolio, interest income and
expenses.

ESTIMATED CURRENT RETURN equals the estimated annual cash to be received from
the bonds in the Fund less estimated annual Fund expenses, divided by the Unit
Price (including the maximum sales fee):

<TABLE>
<S>              <C>  <C>
Estimated Annual         Estimated
Interest Income   -   Annual Expenses
- -------------------------------------
             Unit Price
</TABLE>

ESTIMATED LONG TERM RETURN is a measure of the estimated return over the
estimated life of the Fund. Unlike Estimated Current Return, Estimated Long Term
Return reflects maturities, discounts and premiums of the bonds in the Fund. It
is an average of the yields to maturity (or in certain cases, to an earlier call
date) of the individual bonds in the portfolio, adjusted to reflect the Fund's
maximum sales fee and estimated expenses. We calculate the average yield for the
portfolio by weighting each bond's yield by its market value and the time
remaining to the call or maturity date.

Yields on individual bonds depend on many factors including general conditions
of the bond markets, the size of a particular offering and the maturity and
quality rating of the particular issues. Yields can vary among bonds with
similar maturities, coupons and ratings.

These return quotations are designed to be comparative rather than predictive.

RECORDS AND REPORTS

You will receive:
- - a monthly statement of income payments and any principal payments;
- - a notice from the Trustee when new bonds are deposited in exchange or
  substitution for bonds originally deposited;
- - an annual report on Fund activity; and
- - annual tax information. THIS WILL ALSO BE SENT TO THE IRS. YOU MUST REPORT THE
  AMOUNT OF TAX-EXEMPT INTEREST RECEIVED DURING THE YEAR.

You may request:
- - copies of bond evaluations to enable you to comply with federal and state tax
  reporting requirements; and
- - audited financial statements of the Fund.

You may inspect records of Fund transactions at the Trustee's office during
regular business hours.

                                       7
<PAGE>
THE RISKS YOU FACE

INTEREST RATE RISK

Investing involves risks, including the risk that your investment will decline
in value if interest rates rise. Generally, bonds with longer maturities will
change in value more than bonds with shorter maturities. Bonds in the Fund are
more likely to be called when interest rates decline. This would result in early
returns of principal to you and may result in early termination of the Fund. Of
course, we cannot predict how interest rates may change.

CALL RISK

Many bonds can be prepaid or "called" by the issuer before their stated
maturity.

For example, an issuer might call its bonds if it no longer needs the money for
the original purpose or, during periods of falling interest rates, if the
issuer's bonds have a coupon higher than current market rates. If the bonds are
called, your income will decline and you may not be able to reinvest the money
you receive at as high a yield or as long a maturity. An early call at par of a
premium bond will reduce your return.

REDUCED DIVERSIFICATION RISK

If many investors sell their units, the Fund will have to sell bonds. This could
reduce the diversification of your investment and increase your share of Fund
expenses.

LIQUIDITY RISK

The bonds will generally trade in the over-the-counter market. We cannot assure
you that a liquid trading market will exist, especially since current law may
restrict the Fund from selling bonds to any Sponsor. The value of the bonds, and
of your investment, may be reduced if trading in bonds is limited or absent.

CONCENTRATION RISK

When a certain type of bond makes up 25% or more of the portfolio, the Fund is
said to be "concentrated" in that bond type, which makes the Fund less
diversified.

Here is what you should know about the Fund's concentration in refunded bonds.
Refunded bonds are typically:
  - backed by direct obligations of the U.S. government; or
  - in some cases, backed by obligations guaranteed by the U.S. government and
    placed in escrow with an independent trustee;
  - noncallable prior to maturity; but
  - sometimes called for redemption prior to maturity.

Changes to the portfolio from bond redemptions, maturities and sales may affect
the Fund's concentration over time.

BOND QUALITY RISK

A reduction in a bond's rating may decrease its value and, indirectly, the value
of your investment in the Fund.

INSURANCE RELATED RISK

The bonds are backed by insurance companies (as shown under Defined Portfolio).
Insurance policies generally make payments only according to a bond's original
payment schedule and do not make early payments when a bond defaults or becomes
taxable. Although the federal government does not regulate the insurance
business, various state laws and federal initiatives and tax law changes could
significantly affect the insurance business. The claims-paying ability of the
insurance companies is generally

                                       8
<PAGE>
rated A or better by Standard & Poor's or another nationally recognized rating
organization. The insurance company ratings are subject to change at any time at
the discretion of the rating agencies.

LITIGATION AND LEGISLATION RISKS

We do not know of any pending litigation that might have a material adverse
effect upon the Fund.

Future tax legislation could affect the value of the portfolio by:
  - limiting real property taxes,
  - reducing tax rates,
  - imposing a flat or other form of tax, or
  - exempting investment income from tax.

SELLING OR EXCHANGING UNITS

You can sell your units at any time for a price based on net asset value. Your
net asset value is calculated each business day by:
  - ADDING the value of the bonds, net accrued interest, cash and any other Fund
    assets;
  - SUBTRACTING accrued but unpaid Fund expenses, unreimbursed Trustee advances,
    cash held to buy back units or for distribution to investors and any other
    Fund liabilities; and
  - DIVIDING the result by the number of outstanding units.

Your net asset value when you sell may be more or less than your cost because of
sales fees, market movements and changes in the portfolio.

SPONSORS' SECONDARY MARKET

While we are not obligated to do so, we will buy back units at net asset value
without any other fee or charge. We may resell the units to other buyers or to
the Trustee. You should consult your financial professional for current market
prices to determine if other broker-dealers or banks are offering higher prices.

We have maintained a secondary market continuously for over 28 years, but we
could discontinue it without prior notice for any business reason.

SELLING UNITS TO THE TRUSTEE

Regardless of whether we maintain a secondary market, you can sell your units to
the Trustee at any time by sending the Trustee a letter (with any outstanding
certificates if you hold unit certificates). You must properly endorse your
certificates (or execute a written transfer instrument with signatures
guaranteed by an eligible institution). Sometimes, additional documents are
needed such as a trust document, certificate of corporate authority, certificate
of death or appointment as executor, administrator or guardian.

Within seven days after your request and the necessary documents are received,
the Trustee will mail a check to you. Contact the Trustee for additional
information.

As long as we are maintaining a secondary market, the Trustee will sell your
units to us at a price based on net asset value. If there is no secondary
market, the Trustee may sell your units in the over-the-counter market for a
higher price, but it is not obligated to do so. In that case, you will receive
the net proceeds of the sale.

If the Fund does not have cash available to pay you for units you are selling,
the agent for the Sponsors will select bonds to be sold. Bonds will be selected
based on market and credit factors. These sales could be made at times when the
bonds would not otherwise

                                       9
<PAGE>
be sold and may result in your receiving less than the unit par value and also
reduce the size and diversity of the Fund.

If you acquire 25% or more of the outstanding units of the Fund and you sell
units with a value exceeding $250,000, the Trustee may choose to pay you "in
kind" by distributing bonds and cash with a total value equal to the price of
those units. The Trustee will try to distribute bonds in the portfolio pro rata,
but it reserves the right to distribute only one or a few bonds. The Trustee
will act as your agent in an in kind distribution and will either hold the bonds
for your account or sell them as you instruct. You must pay any transaction
costs as well as transfer and ongoing custodial fees on sales of bonds
distributed in kind.

There could be a delay in paying you for your units:
  - if the New York Stock Exchange is closed (other than customary weekend and
    holiday closings);
  - if the SEC determines that trading on the New York Stock Exchange is
    restricted or that an emergency exists making sale or evaluation of the
    bonds not reasonably practicable; and
  - for any other period permitted by SEC order.

EXCHANGE OPTION

You may exchange units of certain Defined Asset Funds for units of this Fund at
a maximum exchange fee of 1.90%. You may exchange units of this Fund for units
of certain other funds at a reduced sales fee if your investment goals change.
To exchange units, you should talk to your financial professional about what
funds are exchangeable, suitable and currently available.

Normally, an exchange is taxable and you must recognize any gain or loss on the
exchange. However, the IRS may try to disallow a loss if the portfolios of the
two funds are not materially different; you should consult your own tax adviser.

We may amend or terminate this exchange option at any time without notice.

HOW THE FUND WORKS

PRICING

The price of a unit includes interest accrued on the bonds, less expenses, from
the most recent Record Day up to, but not including, the settlement date, which
is usually three business days after the purchase date of the unit.

A portion of the price of a unit consists of cash so that the Trustee can
provide you with regular monthly income. When you sell your units you will
receive your share of this cash.

In addition, as with mutual funds, the Fund (and therefore the investors) pay
all or some of the costs of organizing the Fund including:
  - cost of initial preparation of legal documents;
  - federal and state registration fees;
  - initial fees and expenses of the Trustee;
  - initial audit; and
  - legal expenses and other out-of-pocket expenses.

These costs are amortized over the first five years of the Fund.

EVALUATIONS

An independent Evaluator values the bonds on each business day (excluding
Saturdays, Sundays and the following holidays as

                                       10
<PAGE>
observed by the New York Stock Exchange: New Year's Day, Presidents' Day, Martin
Luther King, Jr. Day, Good Friday, Memorial Day, Independence Day, Labor Day,
Thanksgiving and Christmas). Bond values are based on current bid or offer
prices for the bonds or comparable bonds. In the past, the difference between
bid and offer prices of publicly offered tax-exempt bonds has ranged from 0.5%
of face amount on actively traded issues to 3.5% on inactively traded issues;
the difference has averaged between 1 and 2%.

INCOME

The Trustee credits interest to an Income Account and other receipts to a
Capital Account. The Trustee may establish a Reserve Account by withdrawing from
these accounts amounts it considers appropriate to pay any material liability.
These accounts do not bear interest.

EXPENSES

The Trustee is paid monthly. It also benefits when it holds cash for the Fund in
non-interest bearing accounts. The Trustee may also receive additional amounts:
  - to reimburse the Trustee for the Fund's operating expenses;
  - for extraordinary services and costs of indemnifying the Trustee and the
    Sponsors;
  - costs of actions taken to protect the Fund and other legal fees and
    expenses;
  - expenses for keeping the Fund's registration statement current; and
  - Fund termination expenses and any governmental charges.

The Sponsors are currently reimbursed up to 55 CENTS per $1,000 face amount
annually for providing portfolio supervisory, bookkeeping and administrative
services and for any other expenses properly chargeable to the Fund. Legal,
typesetting, electronic filing and regulatory filing fees and expenses
associated with updating the Portfolio's registration statement yearly are also
now chargeable to the Portfolio. While this fee may exceed the amount of these
costs and expenses attributable to this Fund, the total of these fees for all
Series of Defined Asset Funds will not exceed the aggregate amount attributable
to all of these Series for any calendar year. The Fund also pays the Evaluator's
fees.

The Trustee's, Sponsors' and Evaluator's fees may be adjusted for inflation
without investors' approval.

The Sponsors will pay advertising and selling expenses at no charge to the Fund.
If Fund expenses exceed initial estimates, the Fund will owe the excess. The
Trustee has a lien on Fund assets to secure reimbursement of Fund expenses and
may sell bonds if cash is not available.

PORTFOLIO CHANGES

The Sponsors and Trustee are not liable for any default or defect in a bond.

Unlike a mutual fund, the portfolio is designed to remain intact and we may keep
bonds in the portfolio even if their credit quality declines or other adverse
financial circumstances occur. However, we may sell a bond in certain cases if
we believe that certain adverse credit conditions exist or if a bond becomes
taxable.

If we maintain a secondary market in units but are unable to sell the units that
we buy in the secondary market, we will redeem units, which may affect the
composition of the portfolio. Units offered in the secondary

                                       11
<PAGE>
market may not represent the same face amount of bonds that they did originally.

We decide whether or not to offer units for sale that we acquire in the
secondary market after reviewing:
  - diversity of the portfolio;
  - size of the Fund relative to its original size;
  - ratio of Fund expenses to income;
  - current and long-term returns;
  - degree to which units may be selling at a premium over par; and
  - cost of maintaining a current prospectus.

FUND TERMINATION

The Fund will terminate following the stated maturity or sale of the last bond
in the portfolio. The Fund may also terminate earlier with the consent of
investors holding 51% of the units or if total assets of the Fund have fallen
below 40% of the face amount of bonds deposited. We will decide whether to
terminate the Fund early based on the same factors used in deciding whether or
not to offer units in the secondary market.

When the Fund is about to terminate you will receive a notice, and you will be
unable to sell your units after that time. On or shortly before termination, we
will sell any remaining bonds, and you will receive your final distribution. Any
bond that cannot be sold at a reasonable price may continue to be held by the
Trustee in a liquidating trust pending its final sale.

You will pay your share of the expenses associated with termination, including
brokerage costs in selling bonds. This may reduce the amount you receive as your
final distribution.

CERTIFICATES

Certificates for units are issued on request. You may transfer certificates by
complying with the requirements for redeeming certificates, described above. You
can replace lost or mutilated certificates by delivering satisfactory indemnity
and paying the associated costs.

TRUST INDENTURE

The Fund is a "unit investment trust" governed by a Trust Indenture, a contract
among the Sponsors, the Trustee and the Evaluator, which sets forth their duties
and obligations and your rights. A copy of the Indenture is available to you on
request to the Trustee. The following summarizes certain provisions of the
Indenture.

The Sponsors and the Trustee may amend the Indenture without your consent:
  - to cure ambiguities;
  - to correct or supplement any defective or inconsistent provision;
  - to make any amendment required by any governmental agency; or
  - to make other changes determined not to be materially adverse to your best
    interest (as determined by the Sponsors).

Investors holding 51% of the units may amend the Indenture. Every investor must
consent to any amendment that changes the 51% requirement. No amendment may
reduce your interest in the Fund without your written consent.

The Trustee may resign by notifying the Sponsors. The Sponsors may remove the
Trustee without your consent if:
  - it fails to perform its duties and the Sponsors determine that its
    replacement is in your best interest; or

                                       12
<PAGE>
  - it becomes incapable of acting or bankrupt or its affairs are taken over by
    public authorities.

Investors holding 51% of the units may remove the Trustee. The Evaluator may
resign or be removed by the Sponsors and the Trustee without the consent of
investors. The resignation or removal of either becomes effective when a
successor accepts appointment. The Sponsors will try to appoint a successor
promptly; however, if no successor has accepted within 30 days after notice of
resignation, the resigning Trustee or Evaluator may petition a court to appoint
a successor.

Any Sponsor may resign as long as one Sponsor with a net worth of $2 million
remains and agrees to the resignation. The remaining Sponsors and the Trustee
may appoint a replacement. If there is only one Sponsor and it fails to perform
its duties or becomes bankrupt the Trustee may:
  - remove it and appoint a replacement Sponsor;
  - liquidate the Fund; or
  - continue to act as Trustee without a Sponsor.

Merrill Lynch, Pierce, Fenner & Smith Incorporated acts as agent for the
Sponsors.

The Trust Indenture contains customary provisions limiting the liability of the
Trustee, the Sponsors and the Evaluator.

LEGAL OPINION

Davis Polk & Wardwell, 450 Lexington Avenue, New York, New York 10017, as
special counsel for the Sponsors, has given an opinion that the units are
validly issued.

AUDITORS

Deloitte & Touche LLP, 2 World Financial Center, New York, New York 10281,
independent accountants, audited the Statement of Condition included in this
prospectus.

SPONSORS

The Sponsors are:

MERRILL LYNCH, PIERCE, FENNER & SMITH INCORPORATED (a wholly-owned subsidiary of
Merrill Lynch & Co., Inc.)
P.O. Box 9051,
Princeton, NJ 08543-9051
SALOMON SMITH BARNEY INC. (an indirectly wholly-owned subsidiary of Citigroup
Inc.)
388 Greenwich Street--23rd Floor,
New York, NY 10013
DEAN WITTER REYNOLDS INC. (a principal operating subsidiary of Morgan Stanley
Dean Witter & Co.)
Two World Trade Center--59th Floor,
New York, NY 10048
PRUDENTIAL SECURITIES INCORPORATED (an indirect wholly-owned subsidiary of the
Prudential Insurance Company of America)
One New York Plaza
New York, NY 10292
PAINEWEBBER INCORPORATED (a wholly-owned subsidiary of PaineWebber Group Inc.)
1285 Avenue of the Americas,
New York, NY 10019

Each Sponsor is a Delaware corporation and it, or its predecessor, has acted as
sponsor to many unit investment trusts. As a registered broker-dealer each
Sponsor buys and sells securities (including investment company shares) for
others (including investment companies) and participates as an underwriter in
various selling groups.

                                       13
<PAGE>
TRUSTEE

The Bank of New York, 101 Barclay Street,
17 W, New York, New York 10268, is the Trustee. It is supervised by the Federal
Deposit Insurance Corporation, the Board of Governors of the Federal Reserve
System and New York State banking authorities.

UNDERWRITERS' AND SPONSORS' PROFITS

Underwriters receive sales charges when they sell units. The Sponsors also
realized a profit or loss on the initial deposit of the bonds. Any cash made
available by you to the Sponsors before the settlement date for those units may
be used in the Sponsors' businesses to the extent permitted by federal law and
may benefit the Sponsors.

A Sponsor or Underwriter may realize profits or sustain losses on bonds in the
Fund which were acquired from underwriting syndicates of which it was a member.

In maintaining a secondary market, the Sponsors will also realize profits or
sustain losses in the amount of any difference between the prices at which they
buy units and the prices at which they resell or redeem them.

PUBLIC DISTRIBUTION

The Sponsors do not intend to qualify units for sale in any foreign countries.
This prospectus does not constitute an offer to sell units in any country where
units cannot lawfully be sold.

CODE OF ETHICS

The Fund and the Agent for the Sponsors have each adopted a code of ethics
requiring reporting of personal securities transactions by its employees with
access to information on Fund transactions. Subject to certain conditions, the
codes permit employees to invest in Fund securities for their own accounts. The
codes are designed to prevent fraud, deception and misconduct against the Fund
and to provide reasonable standards of conduct. These codes are on file with the
Commission and you may obtain a copy by contacting the Commission at the address
listed on the back cover of this prospectus.

YEAR 2000 ISSUES

Many computer systems were designed in such a way that they may be unable to
distinguish between the year 2000 and the year 1900 (commonly known as the "Year
2000 Problem"). To date we are not aware of any major operational difficulties
resulting from the computer system changes necessary to prepare for the Year
2000. However, there can be no assurance that the Year 2000 Problem will not
adversely affect the issuers of the bonds contained in the Portfolio. We cannot
predict whether any impact will be material to the Fund as a whole.

TAXES

The following summary describes some of the important income tax consequences of
holding units. It assumes that you are not a dealer, financial institution,
insurance company or other investor with special circumstances or subject to
special rules. You should consult your own tax adviser about your particular
circumstances.

At the date of issue of each bond, counsel for the issuer delivered an opinion
to the effect that interest on the bond is exempt from regular federal income
tax. However, interest may be subject to state and local

                                       14
<PAGE>
taxes and may be taken into account in determining your preference items for
alternative minumum tax purposes. Neither we nor our counsel have reviewed the
issuance of the bonds, related proceedings or the basis for the opinions of
counsel for the issuers. We cannot assure you that the issuer (or other users)
have complied or will comply with any requirements necessary for a bond to be
tax-exempt. If any of the bonds were determined not to be tax-exempt, you could
be required to pay income tax for current and prior years, and if the Fund were
to sell the bond, it might have to sell it at a substantial discount.

In the opinion of our counsel, under existing law:

GENERAL TREATMENT OF THE FUND AND YOUR INVESTMENT

The Fund will not be taxed as a corporation for federal income tax purposes, and
you will be considered to own directly your share of each bond in the Fund.

GAIN OR LOSS UPON DISPOSITION

When all or part of your share of a bond is disposed of (for example, when the
Fund sells, exchanges or redeems a bond or when you sell or exchange your
units), you will generally recognize capital gain or loss. Your gain, however,
will generally be ordinary income to the extent of any accrued "market
discount". Generally you will have market discount to the extent that your basis
in a bond when you purchase a unit is less than its stated redemption price at
maturity (or, if it is an original issue discount bond, the issue price
increased by original issue discount that has accrued on the bond before your
purchase). You should consult your tax adviser in this regard.

If your net long-term capital gains exceed your net short-term capital losses,
the excess may be subject to tax at a lower rate than ordinary income. Any
capital gain from the Fund will be long-term if you are considered to have held
your investment on each bond for more than one year and short-term otherwise. If
you are an individual and sell your units after holding them for more than one
year, you may be entitled to a 20% maximum federal tax rate on any resulting
gains. Consult your tax adviser in this regard. Because the deductibility of
capital losses is subject to limitations, you may not be able to deduct all of
your capital losses.

YOUR BASIS IN THE BONDS

Your aggregate basis in the bonds will be equal to the cost of your units,
including any sales charges and the organizational expenses you pay, adjusted to
reflect any accruals of "original issue discount," "acquisition premium" and
"bond premium". You should consult your tax adviser in this regard.

EXPENSES

If you are not a corporate investor, you will not be entitled to a deduction for
your share of fees and expenses of the Fund. Also, if you borrowed money in
order to purchase or carry your units, you will not be able to deduct the
interest on this borrowing for federal income tax purposes. The IRS may treat
your purchase of units as made with borrowed money even if the money is not
directly traceable to the purchase of units.

STATE AND LOCAL TAXES

Under the income tax laws of the State and City of New York, the Fund will not
be taxed as a corporation. If you are a New York taxpayer, your income from the
Fund

                                       15
<PAGE>
will not be tax-exempt in New York except to the extent that the income is
earned on bonds that are tax-exempt for New York purposes. Depending on where
you live, your income from the Fund may be subject to state and local taxation.
You should consult your tax adviser in this regard.

SUPPLEMENTAL INFORMATION

You can receive at no cost supplemental information about the Fund by calling
the Trustee. The supplemental information includes more detailed risk disclosure
about the types of bonds that may be in the Fund's portfolio, general risk
disclosure concerning any insurance securing certain bonds, and general
information about the structure and operation of the Fund. The supplemental
information is also available from the SEC.

                                       16
<PAGE>

MUNICIPAL INVESTMENT TRUST FUND,
INSURED SERIES - 303,
DEFINED ASSET FUNDS

REPORT OF INDEPENDENT ACCOUNTANTS

The Sponsors, Trustee and Holders
  of Municipal Investment Trust Fund,
  Insured Series - 303,
  Defined Asset Funds:

We have audited the accompanying statement of condition of Municipal Investment
Trust Fund, Insured Series - 303, Defined Asset Funds, including the portfolio,
as of February 29, 2000 and the related statements of operations and of changes
in net assets for the years ended February 29, 2000 and February 28, 1999 and
the period March 20, 1997 to February 28, 1998. These financial statements are
the responsibility of the Trustee. Our responsibility is to express an opinion
on these financial statements based on our audits.

We conducted our audits in accordance with auditing standards generally accepted
in the United States of America. 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. Securities owned at February 29, 2000, as shown in such portfolio,
were confirmed to us by The Bank of New York, the Trustee. An audit also
includes assessing the accounting principles used and significant estimates made
by the Trustee, as well as evaluating the overall financial statement
presentation. We believe that our audits provide a reasonable basis for our
opinion.

In our opinion, the financial statements referred to above present fairly, in
all material respects, the financial position of Municipal Investment Trust
Fund, Insured Series - 303, Defined Asset Funds at February 29, 2000 and the
results of its operations and changes in its net assets for the above-stated
periods in accordance with accounting principles generally accepted in the
United States of America.

DELOITTE & TOUCHE LLP

New York, N.Y.
April 26, 2000


                                      D - 1
<PAGE>

MUNICIPAL INVESTMENT TRUST FUND,
INSURED SERIES - 303,
DEFINED ASSET FUNDS

STATEMENT OF CONDITION
AS OF FEBRUARY 29, 2000

<TABLE>
<S>                                                <C>           <C>
TRUST PROPERTY:
  Investment in marketable securities - at value
    (cost $8,383,470)(Note 1)......................                  $8,304,215
  Accrued interest receivable......................                     116,573
  Accrued interest receivable on segregated bonds..                       1,577
  Deferred organization costs (Note 6).............                       4,038
                                                                   -------------

              Total trust property.................                   8,426,403

LESS LIABILITIES:
  Deferred sales charge............................  $    58,111
  Advance from Trustee.............................        2,561
  Accrued expenses.................................        6,656         67,328
                                                    -------------  -------------

NET ASSETS, REPRESENTED BY:
  8,612 units of fractional undivided
    interest outstanding (Note 3)..................    8,328,759
  Undistributed net investment income..............       30,316
                                                    -------------
                                                                      $8,359,075
                                                                   =============
UNIT VALUE ($8,359,075/8,612 units)................                     $970.63
                                                                   =============

</TABLE>
                       See Notes to Financial Statements.


                                      D - 2
<PAGE>

MUNICIPAL INVESTMENT TRUST FUND,
INSURED SERIES - 303,
DEFINED ASSET FUNDS

STATEMENTS OF OPERATIONS

<TABLE>
<CAPTION>
                                                                            March 20,
                                                                                1997
                                             Year Ended    Year Ended             to
                                             February 29,  February 28,   February 28,
                                                 2000         1999               1998
                                             -----------------------------------------
<S>                                        <C>          <C>          <C>
INVESTMENT INCOME:
  Interest income...........................   $ 495,806     $525,085   $  534,723
  Interest income on segregated bonds.......       6,216       12,268       16,198
  Trustee's fees and expenses...............      (9,853)      (9,176)     (11,435)
  Sponsors' fees............................      (4,061)      (4,509)      (4,424)
  Organizational expenses...................      (2,019)      (2,019)      (2,019)
                                             -----------------------------------------
  Net investment income.....................     486,089      521,649      533,043
                                             -----------------------------------------

REALIZED AND UNREALIZED GAIN (LOSS)
  ON INVESTMENTS:
  Realized gain on securities sold
    or redeemed.............................      44,636       32,311       12,895
  Unrealized appreciation (depreciation)
    of investments..........................    (919,192)     212,569      627,368
                                             -----------------------------------------

  Net realized and unrealized gain (loss)
    on investments..........................    (874,556)     244,880      640,263
                                             -----------------------------------------

NET INCREASE (DECREASE) IN NET ASSETS
  RESULTING FROM OPERATIONS.................   $(388,467)    $766,529   $1,173,306
                                             =========================================

</TABLE>
                       See Notes to Financial Statements.


                                      D - 3
<PAGE>

MUNICIPAL INVESTMENT TRUST FUND,
INSURED SERIES - 303,
DEFINED ASSET FUNDS

STATEMENTS OF CHANGES IN NET ASSETS

<TABLE>
<CAPTION>
                                                                              March 20,
                                                                                   1997
                                                Year Ended   Year Ended              to
                                               February 29,  February 28,   February 28,
                                                   2000         1999               1998
                                               -----------------------------------------
<S>                                          <C>          <C>          <C>
OPERATIONS:
  Net investment income.......................  $   486,089   $   521,649    $   533,043
  Realized gain on securities sold
    or redeemed...............................       44,636        32,311         12,895
  Unrealized appreciation (depreciation)
    of investments............................     (919,192)      212,569        627,368
                                               -----------------------------------------
  Net increase (decrease) in net assets
    resulting from operations.................     (388,467)      766,529      1,173,306
                                               -----------------------------------------

DISTRIBUTIONS TO HOLDERS (Note 2):
  Income......................................     (480,031)     (507,763)      (484,743)
  Principal...................................      (14,030)      (28,255)
                                               -----------------------------------------
  Total distributions.........................     (494,061)     (536,018)      (484,743)
                                               -----------------------------------------
CAPITAL SHARE TRANSACTIONS - Redemptions of
  652, 518 and 313 units, respectively........     (660,375)     (544,405)      (327,644)

DEFERRED SALES CHARGE (Note 5)................     (138,960)     (154,500)      (160,815)
                                               -----------------------------------------
NET INCREASE (DECREASE) IN NET ASSETS.........   (1,681,863)     (468,394)       200,104

NET ASSETS AT BEGINNING OF PERIOD.............   10,040,938    10,509,332     10,309,228
                                               -----------------------------------------
NET ASSETS AT END OF PERIOD...................  $ 8,359,075   $10,040,938    $10,509,332
                                               =========================================
PER UNIT:
  Income distributions during period..........       $53.73        $53.79         $48.31
                                               =========================================
  Principal distributions during period.......        $1.60         $3.05
                                               =========================================
  Net asset value at end of period............      $970.63     $1,083.87      $1,074.35
                                               =========================================
TRUST UNITS OUTSTANDING AT END OF PERIOD......        8,612         9,264          9,782
                                               =========================================
</TABLE>
                       See Notes to Financial Statements.


                                      D - 4
<PAGE>

MUNICIPAL INVESTMENT TRUST FUND,
INSURED SERIES - 303,
DEFINED ASSET FUNDS

NOTES TO FINANCIAL STATEMENTS

  1.  SIGNIFICANT ACCOUNTING POLICIES

      The Fund is registered under the Investment Company Act of 1940 as a Unit
      Investment Trust. The following is a summary of significant accounting
      policies consistently followed by the Fund in the preparation of its
      financial statements. The policies are in accordance with accounting
      principles generally accepted in the United States of America.

      (a) Securities are stated at value as determined by the Evaluator based on
          bid side evaluations for the securities, except that value on March
          20, 1997 was based upon offer side evaluations at March 18, 1997, the
          day prior to the Date of Deposit. Cost of securities at March 20, 1997
          was also based on such offer side evaluations.

      (b) The Fund is not subject to income taxes. Accordingly, no
          provision for such taxes is required.

      (c) Interest income is recorded as earned.

  2.  DISTRIBUTIONS

      A distribution of net investment income is made to Holders each month.
      Receipts other than interest, after deductions for redemptions and
      applicable expenses, are also distributed periodically.

  3.  NET CAPITAL
<TABLE>
<S>                                                      <C>
      Cost of 8,612 units at Date of Deposit..............    $8,794,757
      Redemptions of units - net cost of 1,483 units
        redeemed less redemption amounts..................       (14,707)
      Realized gain on securities sold or redeemed........        89,842
      Principal distributions.............................       (42,285)
      Interest income on segregated bonds.................        34,682
      Deferred sales charge...............................      (454,275)
      Net unrealized depreciation of investments..........       (79,255)
                                                           --------------

      Net capital applicable to Holders...................    $8,328,759
                                                           ==============
</TABLE>

  4.  INCOME TAXES

      As of February 29, 2000, net unrealized depreciation of investments, based
      on cost for Federal income tax purposes, aggregated $79,255 of which
      $118,281 related to appreciated securities and $197,536 related to
      depreciated securities. The cost of investment securities for Federal
      income tax purposes was $8,383,470 at February 29, 2000.


                                      D - 5
<PAGE>
MUNICIPAL INVESTMENT TRUST FUND,
INSURED SERIES - 303,
DEFINED ASSET FUNDS

NOTES TO FINANCIAL STATEMENTS

  5.  DEFERRED SALES CHARGE

      The sales charges are being paid for with the interest received and by
      periodic sales of these bonds. A deferred sales charge of $3.75 per unit
      is charged on a quarterly basis, and paid to the sponsors annually by the
      Trustee on behalf of the Holders, up to an aggregate of $45.00 per unit
      over the first three years of the life of the Fund. Should a Holder redeem
      units prior to the third anniversary of the Fund, the remaining balance of
      the deferred sales charge will be charged.

  6.  DEFERRED ORGANIZATIONAL COSTS

      Organizational costs have been deferred and are being amortized over five
      years.

                                      D - 6
<PAGE>

MUNICIPAL INVESTMENT TRUST FUND,
INSURED SERIES - 303,
DEFINED ASSET FUNDS

PORTFOLIO
AS OF FEBRUARY 29, 2000
<TABLE>
<CAPTION>
                                         Rating                                       Optional
    Portfolio No. and Title of             of            Face                         Redemption
            Securities(4)                Issues(1)       Amount  Coupon Maturities(3) Provisions(3)          Cost(2)      Value(2)
            -------------                ---------       ------  ------ ------------- -------------          -------      --------
<S>                                      <C>       <C>           <C>       <C>        <C>            <C>           <C>
 1 Jefferson Cnty., AL, Sewer Rev.         AAA       $  895,000   5.750%   2022       02/01/07            $  891,402    $  869,985
   Warrants, Ser. 1997 D (Financial                                                   @ 101.000
   Guaranty Ins.)

 2 Alaska Hsg. Fin. Corp., Govt.           AAA        1,000,000   5.875    2024       12/01/05               996,500       980,720
   Purp. Bonds, Ser. 1995 A (MBIA                                                     @ 102.000
   Ins.)

 3 City and County of Denver, CO,          AAA        1,000,000   5.500    2025       11/15/06               965,000       923,740
   Dept. of Aviation, Arpt. Sys. Rev.                                                 @ 101.000
   Bond, Ser. 1996 D (MBIA Ins.)

 4 The School Bd. of Dade Cnty.,           AAA          550,000   5.500    2025(5)    05/01/06               530,904       566,099
   FL, Certs of Part., Ser. 1996 A                                                    @ 101.000
   (AMBAC Ins.)

 5 City of Chicago, IL, Chicago Sch.       AAA          325,000   6.000    2026(5)    12/01/06               330,431       346,135
   Reform. Brd. of Trustee of the Brd.                                                @ 102.000
   of Edcu., Unltd. Tax G.O. Bonds
   (Dedicated Tax Revenues) Ser. 1996
   (MBIA Ins.)

 6 City of Boston, MA, Indl. Dev.          AAA          750,000   5.250    2026       10/01/04               687,060       655,943
   Fin. Auth. (Massachusetts Coll.                                                    @ 102.000
   of Pharmacy Proj.), Rev. Bonds
   Ser. 1993 A (Connie Lee Ins.)

 7 City of Grand Forks, ND, (The           AAA          780,000   5.625    2029       12/15/07               760,000       732,365
   Aurora Proj.) Sales Tax Rev. Bonds,                                                @ 100.000
   Ser 1997 A (MBIA Ins.)

 8 Delaware Cnty. Auth., PA, (Neumann      AAA          600,000   5.625    2025(5)    10/01/05               585,420       615,708
   College) Coll. Rev. Bonds, Ser.                                                    @ 100.000
   1995 (Connie Lee Ins.)

</TABLE>


                                      D - 7
<PAGE>

MUNICIPAL INVESTMENT TRUST FUND,
INSURED SERIES - 303,
DEFINED ASSET FUNDS

PORTFOLIO
AS OF FEBRUARY 29, 2000
<TABLE>
<CAPTION>
                                         Rating                                       Optional
    Portfolio No. and Title of             of            Face                         Redemption
            Securities(4)                Issues(1)       Amount  Coupon Maturities(3) Provisions(3)          Cost(2)      Value(2)
            -------------                ---------       ------  ------ ------------- -------------          -------      --------
<S>                                      <C>       <C>           <C>       <C>        <C>            <C>           <C>
 9 City of San Antonio TX, (Henry B.,      AAA       $1,000,000   5.700%   2026       08/15/06            $  985,900    $  949,530
   Gonzalez Conv. Ctr. Expansion                                                      @ 102.000
   Proj.), Hotel Occup. Tax Rev.
   Bonds, Ser. 1996 (Financial
   Guaranty Ins.)

10 Wisconsin Hlth. & Educl. Facs.          AAA          510,000   5.500    2026       12/01/06               484,939       464,222
   Auth. (The Medical College of                                                      @ 102.000
   Wisconsin, Inc. Proj.), Rev. Bonds,
   Ser. 1996 (MBIA Ins.)

11 Wisconsin Hlth. & Educl. Facs.          AAA          250,000   5.750    2027       03/01/07               241,345       238,105
   Auth. (The Medical College of                                                      @ 102.000
   Wisconsin, Inc. Proj.), Rev.
   Bonds, Ser. 1997 (MBIA Ins.)

12 Southeast, WI, Professional             AAA          815,000   5.800    2026(5)    03/13/07               815,000       851,626
   Bonds, Baseball Park Dist.,                                                        @ 101.000
   Sales Tax Rev. Ser. 1996
   (MBIA Ins.)

13 Village of Menomonee Falls, WI,         AAA          110,000   4.300    2000       None                   109,569       110,037
   Waukesha Cnty., Sewerage Sys.
   Rev. Bonds (AMBAC Ins.)(6)

                                                   --------------                                      -------------- -------------
TOTAL                                                $8,585,000                                           $8,383,470    $8,304,215
                                                   ==============                                      ============== =============
</TABLE>
                             See Notes to Portfolio.


                                      D - 8
<PAGE>

MUNICIPAL INVESTMENT TRUST FUND,
INSURED SERIES - 303,
DEFINED ASSET FUNDS

NOTES TO PORTFOLIO
AS OF FEBRUARY 29, 2000

   (1) The ratings of the bonds are by Standard & Poor's Ratings Group, or by
       Moody's Investors Service, Inc. if followed by "(m)", or by Fitch
       Investors Service, Inc. if followed by "(f)"; "NR" indicates that this
       bond is not currently rated by any of the above-mentioned rating
       services. These ratings have been furnished by the Evaluator but not
       confirmed with the rating agencies.

   (2) See Notes to Financial Statements.

   (3) Optional redemption provisions, which may be exercised in whole or in
       part, are initially at prices of par plus a premium, then subsequently at
       prices declining to par. Certain securities may provide for redemption at
       par prior or in addition to any optional or mandatory redemption dates or
       maturity, for example, through the operation of a maintenance and
       replacement fund, if proceeds are not able to be used as contemplated,
       the project is condemned or sold or the project is destroyed and
       insurance proceeds are used to redeem the securities. Many of the
       securities are also subject to mandatory sinking fund redemption
       commencing on dates which may be prior to the date on which securities
       may be optionally redeemed. Sinking fund redemptions are at par and
       redeem only part of the issue. Some of the securities have mandatory
       sinking funds which contain optional provisions permitting the issuer to
       increase the principal amount of securities called on a mandatory
       redemption date. The sinking fund redemptions with optional provisions
       may, and optional refunding redemptions generally will, occur at times
       when the redeemed securities have an offering side evaluation which
       represents a premium over par. To the extent that the securities were
       acquired at a price higher than the redemption price, this will represent
       a loss of capital when compared with the Public Offering Price of the
       Units when acquired. Distributions will generally be reduced by the
       amount of the income which would otherwise have been paid with respect to
       redeemed securities and there will be distributed to Holders any
       principal amount and premium received on such redemption after satisfying
       any redemption requests for Units received by the Fund. The estimated
       current return may be affected by redemptions.

   (4) Insured by AAA-rated insurance companies that guarantee timely payments
       of principal and interest on the bonds (but not Fund units or the market
       value of the bonds they mature).

   (5) Bonds with an aggregate face amount of $2,290,000 have been pre-refunded
       and are expected to be called for redemption on the optional redemption
       provision dates shown.

   (6) It is anticipated that interest and principal received from these bonds
       will be applied to the payment of the Trust's deferred sales charges.


                                      D - 9
<PAGE>
DEFINED ASSET FUNDS-SM-

<TABLE>
<S>                                      <C>
HAVE QUESTIONS ?                         MUNICIPAL INVESTMENT TRUST FUND
Request the most recent free             INSURED SERIES--303
Information Supplement                   (A Unit Investment Trust)
that gives more details about            ---------------------------------------
the Fund, by calling:                    This Prospectus does not contain
The Bank of New York                     complete information about the
1-800-221-7771                           investment company filed with the
                                         Securities and Exchange Commission in
                                         Washington, D.C. under the:
                                         - Securities Act of 1933 (file no.
                                         333-19657) and
                                         - Investment Company Act of 1940 (file
                                         no. 811-1777).
                                         TO OBTAIN COPIES AT PRESCRIBED RATES--
                                         WRITE: Public Reference Section of the
                                         Commission
                                         450 Fifth Street, N.W., Washington,
                                         D.C. 20549-6009
                                         CALL: 1-800-SEC-0330.
                                         VISIT: http://www.sec.gov.
                                         ---------------------------------------
                                         No person is authorized to give any
                                         information or representations about
                                         this Fund not contained in this
                                         Prospectus or the Information
                                         Supplement, and you should not rely on
                                         any other information.
                                         ---------------------------------------
                                         When units of this Fund are no longer
                                         available, this Prospectus may be used
                                         as a preliminary prospectus for a
                                         future series, but some of the
                                         information in this Prospectus will be
                                         changed for that series.
                                         UNITS OF ANY FUTURE SERIES MAY NOT BE
                                         SOLD NOR MAY OFFERS TO BUY BE ACCEPTED
                                         UNTIL THAT SERIES HAS BECOME EFFECTIVE
                                         WITH THE SECURITIES AND EXCHANGE
                                         COMMISSION. NO UNITS CAN BE SOLD IN ANY
                                         STATE WHERE A SALE WOULD BE ILLEGAL.
                                                                     11537--5/00
</TABLE>



© 2022 IncJournal is not affiliated with or endorsed by the U.S. Securities and Exchange Commission