<PAGE> PAGE 1
000 A000000 12/31/1999
000 C000000 0000816153
000 D000000 N
000 E000000 NF
000 F000000 Y
000 G000000 N
000 H000000 N
000 I000000 6.1
000 J000000 A
001 A000000 THORNBURG INVESTMENT TRUST
001 B000000 811-5201
001 C000000 5059840200
002 A000000 119 E. MARCY ST., SUITE 202
002 B000000 SANTA FE
002 C000000 NM
002 D010000 87124
003 000000 N
004 000000 N
005 000000 N
006 000000 N
007 A000000 Y
007 B000000 1
007 C010100 1
007 C020100 THORNBURG NEW YORK INTERMEDIATE MUNI FUND
007 C030100 N
007 C010200 2
007 C010300 3
007 C010400 4
007 C010500 5
007 C010600 6
007 C010700 7
007 C010800 8
007 C010900 9
007 C011000 10
008 A00AA01 THORNBURG MANAGEMENT COMPANY
008 B00AA01 A
008 C00AA01 801-17853
008 D01AA01 SANTA FE
008 D02AA01 NM
008 D03AA01 87501
011 A00AA01 THORNBURG SECURITIES CORPORATION
011 B00AA01 8-31249
011 C01AA01 SANTA FE
011 C02AA01 NM
011 C03AA01 87501
015 A00AA01 STATE STREET BANK & TRUST
015 B00AA01 C
015 C01AA01 NORTH QUINCY
015 C02AA01 NM
015 C03AA01 02171
015 E06AA01 X
<PAGE> PAGE 2
018 00AA00 Y
019 A00AA00 Y
019 B00AA00 10
019 C00AA00 -THORNBURG
020 C000001 0
020 C000002 0
020 C000003 0
020 C000004 0
020 C000005 0
020 C000006 0
020 C000007 0
020 C000008 0
020 C000009 0
020 C000010 0
021 000000 0
022 A000001 PAINE WEBBER INC.
022 B000001 13-2638166
022 C000001 4200
022 D000001 2700
022 A000002 MORGAN STANLEY
022 B000002 13-2655998
022 C000002 656
022 D000002 1071
022 A000003 BEAR STREANS SEC
022 B000003 13-3299429
022 C000003 700
022 D000003 400
022 A000004 GRUNTAL AND CO.
022 B000004 13-3201805
022 C000004 1012
022 D000004 0
022 A000005 BANK OF NEW YORK
022 B000005 13-3878175
022 C000005 1000
022 D000005 0
022 A000006 CAIN BROTHERS AND CO.
022 B000006 13-3960078
022 C000006 983
022 D000006 0
022 A000007 MERRILL LYNCH PIERCE FENNER
022 B000007 13-5674085
022 C000007 0
022 D000007 955
022 A000008 FISERV CORRESPONDENT SER
022 B000008 84-1181516
022 C000008 703
022 D000008 0
022 A000009 A.G. EDWARDS AND SONS INC.
022 B000009 43-0895447
022 C000009 0
022 D000009 691
<PAGE> PAGE 3
022 A000010 STATE STREET BANK AND TRUST
022 B000010 04-1867445
022 C000010 0
022 D000010 492
023 C000000 12016
023 D000000 10703
024 00AA00 N
025 D00AA01 0
025 D00AA02 0
025 D00AA03 0
025 D00AA04 0
025 D00AA05 0
025 D00AA06 0
025 D00AA07 0
025 D00AA08 0
026 A000000 N
026 B000000 N
026 C000000 N
026 D000000 Y
026 E000000 N
026 F000000 N
026 G010000 N
026 G020000 N
026 H000000 N
027 000000 Y
049 00AA00 N
050 00AA00 N
051 00AA00 N
052 00AA00 N
053 A00AA00 Y
053 B00AA00 Y
053 C00AA00 N
054 A00AA00 N
054 B00AA00 N
054 C00AA00 N
054 D00AA00 N
054 E00AA00 N
054 F00AA00 N
054 G00AA00 Y
054 H00AA00 N
054 I00AA00 N
054 J00AA00 Y
054 K00AA00 N
054 L00AA00 N
054 M00AA00 Y
054 N00AA00 N
054 O00AA00 N
055 A00AA00 N
055 B00AA00 N
056 00AA00 N
057 00AA00 N
<PAGE> PAGE 4
058 A00AA00 N
059 00AA00 Y
060 A00AA00 Y
060 B00AA00 Y
061 00AA00 5000
062 A00AA00 Y
062 B00AA00 0.0
062 C00AA00 0.0
062 D00AA00 0.0
062 E00AA00 1.6
062 F00AA00 0.0
062 G00AA00 0.0
062 H00AA00 0.0
062 I00AA00 0.0
062 J00AA00 0.0
062 K00AA00 0.0
062 L00AA00 0.0
062 M00AA00 0.0
062 N00AA00 0.0
062 O00AA00 98.4
062 P00AA00 0.0
062 Q00AA00 0.0
062 R00AA00 0.0
070 A01AA00 Y
070 A02AA00 N
070 B01AA00 N
070 B02AA00 N
070 C01AA00 Y
070 C02AA00 N
070 D01AA00 N
070 D02AA00 N
070 E01AA00 Y
070 E02AA00 N
070 F01AA00 N
070 F02AA00 N
070 G01AA00 N
070 G02AA00 N
070 H01AA00 N
070 H02AA00 N
070 I01AA00 Y
070 I02AA00 N
070 J01AA00 N
070 J02AA00 N
070 K01AA00 N
070 K02AA00 N
070 L01AA00 Y
070 L02AA00 N
070 M01AA00 Y
070 M02AA00 N
070 N01AA00 Y
070 N02AA00 N
<PAGE> PAGE 5
070 O01AA00 Y
070 O02AA00 N
070 P01AA00 N
070 P02AA00 N
070 Q01AA00 N
070 Q02AA00 N
070 R01AA00 Y
070 R02AA00 N
077 A000000 N
078 000000 N
080 A00AA00 NATIONAL UNION FIRE
080 C00AA00 3000
081 A00AA00 Y
081 B00AA00 2
082 A00AA00 Y
082 B00AA00 50
083 A00AA00 N
083 B00AA00 0
084 A00AA00 N
084 B00AA00 0
085 A00AA00 Y
085 B00AA00 N
086 A010000 0
086 A020000 0
086 B010000 0
086 B020000 0
086 C010000 0
086 C020000 0
086 D010000 0
086 D020000 0
086 E010000 0
086 E020000 0
086 F010000 0
086 F020000 0
028 A010100 244
028 A020100 63
028 A030100 0
028 A040100 70
028 B010100 457
028 B020100 65
028 B030100 0
028 B040100 149
028 C010100 145
028 C020100 67
028 C030100 0
028 C040100 142
028 D010100 4
028 D020100 67
028 D030100 0
028 D040100 164
028 E010100 89
<PAGE> PAGE 6
028 E020100 66
028 E030100 0
028 E040100 132
028 F010100 411
028 F020100 65
028 F030100 0
028 F040100 352
028 G010100 1350
028 G020100 393
028 G030100 0
028 G040100 1009
028 H000100 287
029 000100 Y
030 A000100 6
030 B000100 2.00
030 C000100 0.00
031 A000100 0
031 B000100 0
032 000100 6
033 000100 0
034 000100 N
035 000100 0
036 B000100 0
037 000100 N
038 000100 0
039 000100 Y
040 000100 Y
041 000100 Y
042 A000100 0
042 B000100 0
042 C000100 0
042 D000100 100
042 E000100 0
042 F000100 0
042 G000100 0
042 H000100 0
043 000100 31
044 000100 0
045 000100 Y
046 000100 N
047 000100 Y
048 000100 0.000
048 A010100 500000
048 A020100 0.500
048 B010100 500000
048 B020100 0.450
048 C010100 500000
048 C020100 0.400
048 D010100 500000
048 D020100 0.350
048 E010100 0
<PAGE> PAGE 7
048 E020100 0.000
048 F010100 0
048 F020100 0.000
048 G010100 0
048 G020100 0.000
048 H010100 0
048 H020100 0.000
048 I010100 0
048 I020100 0.000
048 J010100 0
048 J020100 0.000
048 K010100 2000000
048 K020100 0.275
063 A000100 0
063 B000100 8.9
064 A000100 Y
064 B000100 N
066 A000100 N
067 000100 N
068 A000100 N
068 B000100 N
069 000100 N
071 A000100 5863
071 B000100 2936
071 C000100 24176
071 D000100 12
072 A000100 6
072 B000100 735
072 C000100 0
072 D000100 0
072 E000100 0
072 F000100 62
072 G000100 16
072 H000100 0
072 I000100 13
072 J000100 14
072 K000100 0
072 L000100 0
072 M000100 0
072 N000100 0
072 O000100 0
072 P000100 0
072 Q000100 1
072 R000100 4
072 S000100 1
072 T000100 31
072 U000100 0
072 V000100 0
072 W000100 1
072 X000100 143
072 Y000100 49
<PAGE> PAGE 8
072 Z000100 641
072AA000100 0
072BB000100 46
072CC010100 0
072CC020100 467
072DD010100 641
072DD020100 0
072EE000100 0
073 A010100 0.3200
073 A020100 0.0000
073 B000100 0.0000
073 C000100 0.0000
074 A000100 112
074 B000100 0
074 C000100 0
074 D000100 25204
074 E000100 0
074 F000100 0
074 G000100 0
074 H000100 0
074 I000100 0
074 J000100 0
074 K000100 0
074 L000100 594
074 M000100 0
074 N000100 25910
074 O000100 990
074 P000100 5
074 Q000100 0
074 R010100 0
074 R020100 0
074 R030100 0
074 R040100 60
074 S000100 0
074 T000100 24855
074 U010100 2052
074 U020100 0
074 V010100 12.11
074 V020100 0.00
074 W000100 0.0000
074 X000100 670
074 Y000100 0
075 A000100 0
075 B000100 24891
076 000100 0.00
SIGNATURE VAN J. BILLOPS
TITLE ASST. VICE PRESIDENT
<TABLE> <S> <C>
<ARTICLE> 6
<CIK> 0000816153
<NAME> THORNBURG INVESTMENT TRUST
<SERIES>
<NUMBER> 1
<NAME> THORNBURG NEW YORK INTERMEDIATE FUND (A)
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> JUN-30-2000
<PERIOD-END> DEC-31-1999
<INVESTMENTS-AT-COST> 24,215,937
<INVESTMENTS-AT-VALUE> 25,203,530
<RECEIVABLES> 594,180
<ASSETS-OTHER> 112,492
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 25,910,202
<PAYABLE-FOR-SECURITIES> 990,327
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 65,252
<TOTAL-LIABILITIES> 1,055,579
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 23,918,157
<SHARES-COMMON-STOCK> 2,051,988
<SHARES-COMMON-PRIOR> 1,992,245
<ACCUMULATED-NII-CURRENT> 0
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> (51,126)
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 987,593
<NET-ASSETS> 24,854,623
<DIVIDEND-INCOME> 0
<INTEREST-INCOME> 734,702
<OTHER-INCOME> 0
<EXPENSES-NET> (93,838)
<NET-INVESTMENT-INCOME> 640,864
<REALIZED-GAINS-CURRENT> (45,445)
<APPREC-INCREASE-CURRENT> (467,171)
<NET-CHANGE-FROM-OPS> 128,248
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> (640,864)
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 110,287
<NUMBER-OF-SHARES-REDEEMED> (82,658)
<SHARES-REINVESTED> 32,113
<NET-CHANGE-IN-ASSETS> 221,601
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> (5,681)
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 62,558
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 142,417
<AVERAGE-NET-ASSETS> 24,891,234
<PER-SHARE-NAV-BEGIN> 12.36
<PER-SHARE-NII> .32
<PER-SHARE-GAIN-APPREC> (.25)
<PER-SHARE-DIVIDEND> (.32)
<PER-SHARE-DISTRIBUTIONS> 0
<RETURNS-OF-CAPITAL> 0
<PER-SHARE-NAV-END> 12.11
<EXPENSE-RATIO> .75
</TABLE>
