<PAGE> PAGE 1
000 A000000 03/31/98
000 C000000 910068
000 D000000 N
000 E000000 NF
000 F000000 Y
000 G000000 N
000 H000000 N
000 I000000 3.0.a
000 J000000 A
001 A000000 HIGH INCOME OPPORTUNITY FUND INC
001 B000000 811-7920
001 C000000 2128166550
002 A000000 388 GREENWICH STREET
002 B000000 NEW YORK
002 C000000 NY
002 D010000 10013
003 000000 N
004 000000 N
005 000000 N
006 000000 N
007 A000000 N
007 B000000 0
007 C010100 1
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 A000001 SMITH BARNEY
008 B000001 A
008 C000001 801-3387
008 D010001 NEW YORK
008 D020001 NY
008 D030001 10013
010 A000001 MUTUAL MANAGEMENT CORPORATION
010 B000001 801-14437
010 C010001 NEW YORK
010 C020001 NY
010 C030001 10013
011 A000001 SMITH BARNEY
011 B000001 8-817777
011 C010001 NEW YORK
011 C020001 NY
011 C030001 10013
012 A000001 FIRST DATA INVESTORS SERVICES GROUP
012 B000001 84-0000000
012 C010001 BOSTON
<PAGE> PAGE 2
012 C020001 MA
012 C030001 02205
013 A000001 KPMG PEAT MARWICK LLP
013 B010001 NEW YORK
013 B020001 NY
013 B030001 10154
015 A000001 PNC BANK
015 B000001 C
015 C010001 PHILADELPHIA
015 C020001 PA
015 C030001 19103
015 E010001 X
018 000000 Y
019 A000000 Y
019 B000000 127
019 C000000 BARNEY0000
020 A000001 BEAR STEARNS
020 B000001 13-3299429
020 C000001 62
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 62
022 A000001 GOLDMAN SACHS
022 B000001 13-5108880
022 C000001 2015722
022 D000001 48119
022 A000002 CHASE SECURITIES
022 B000002 13-3112953
022 C000002 380487
022 D000002 27551
022 A000003 CS FIRST BOSTON
022 B000003 13-5659485
022 C000003 167860
022 D000003 12452
022 A000004 DONALDSON, LUFKIN & JENRETTE
022 B000004 13-2741729
022 C000004 40824
022 D000004 49648
022 A000005 LEHMAN BROTHERS
022 B000005 13-2518466
022 C000005 50221
022 D000005 35975
022 A000006 UBS SECURITIES
022 B000006 13-2932996
<PAGE> PAGE 3
022 C000006 72877
022 D000006 7617
022 A000007 MORGAN STANLEY & CO
022 B000007 13-2655998
022 C000007 55863
022 D000007 12454
022 A000008 MERRIL LYNCHERS
022 B000008 13-5674085
022 C000008 35173
022 D000008 22256
022 A000009 J.P. MORGAN
022 B000009 13-3224016
022 C000009 26278
022 D000009 8463
022 A000010 GRANCHESTER
022 B000010 13-3502273
022 C000010 11280
022 D000010 23172
023 C000000 2856585
023 D000000 247707
024 000000 N
025 D000001 0
025 D000002 0
025 D000003 0
025 D000004 0
025 D000005 0
025 D000006 0
025 D000007 0
025 D000008 0
026 A000000 N
026 B000000 Y
026 C000000 Y
026 D000000 Y
026 E000000 N
026 F000000 N
026 G010000 N
026 G020000 N
026 H000000 N
027 000000 N
028 A010000 0
028 A020000 0
028 A030000 0
028 A040000 0
028 B010000 0
028 B020000 0
028 B030000 0
028 B040000 0
028 C010000 0
028 C020000 0
028 C030000 0
028 C040000 0
<PAGE> PAGE 4
028 D010000 0
028 D020000 0
028 D030000 0
028 D040000 0
028 E010000 0
028 E020000 0
028 E030000 0
028 E040000 0
028 F010000 0
028 F020000 0
028 F030000 0
028 F040000 0
028 G010000 0
028 G020000 0
028 G030000 0
028 G040000 0
028 H000000 0
030 A000000 0
030 B000000 0.00
030 C000000 0.00
031 A000000 0
031 B000000 0
032 000000 0
033 000000 0
035 000000 0
036 B000000 0
038 000000 0
042 A000000 0
042 B000000 0
042 C000000 0
042 D000000 0
042 E000000 0
042 F000000 0
042 G000000 0
042 H000000 0
043 000000 0
044 000000 0
045 000000 Y
046 000000 N
047 000000 Y
048 000000 1.150
048 A010000 0
048 A020000 0.000
048 B010000 0
048 B020000 0.000
048 C010000 0
048 C020000 0.000
048 D010000 0
048 D020000 0.000
048 E010000 0
048 E020000 0.000
<PAGE> PAGE 5
048 F010000 0
048 F020000 0.000
048 G010000 0
048 G020000 0.000
048 H010000 0
048 H020000 0.000
048 I010000 0
048 I020000 0.000
048 J010000 0
048 J020000 0.000
048 K010000 0
048 K020000 0.000
049 000000 N
050 000000 N
051 000000 N
052 000000 N
053 A000000 N
054 A000000 Y
054 B000000 Y
054 C000000 Y
054 D000000 N
054 E000000 N
054 F000000 N
054 G000000 Y
054 H000000 Y
054 I000000 N
054 J000000 Y
054 K000000 N
054 L000000 N
054 M000000 Y
054 N000000 N
054 O000000 N
055 A000000 N
055 B000000 N
056 000000 N
057 000000 N
058 A000000 N
059 000000 Y
060 A000000 Y
060 B000000 Y
061 000000 0
062 A000000 Y
062 B000000 0.0
062 C000000 0.0
062 D000000 2.7
062 E000000 0.0
062 F000000 0.0
062 G000000 0.0
062 H000000 0.0
062 I000000 0.0
062 J000000 0.0
<PAGE> PAGE 6
062 K000000 0.0
062 L000000 0.0
062 M000000 0.0
062 N000000 0.0
062 O000000 0.0
062 P000000 90.0
062 Q000000 2.1
062 R000000 5.3
063 A000000 0
063 B000000 9.1
064 A000000 N
064 B000000 N
066 A000000 N
067 000000 N
068 A000000 N
068 B000000 N
069 000000 N
070 A010000 Y
070 A020000 Y
070 B010000 Y
070 B020000 N
070 C010000 Y
070 C020000 N
070 D010000 N
070 D020000 N
070 E010000 Y
070 E020000 N
070 F010000 N
070 F020000 N
070 G010000 Y
070 G020000 N
070 H010000 Y
070 H020000 N
070 I010000 N
070 I020000 N
070 J010000 Y
070 J020000 Y
070 K010000 N
070 K020000 N
070 L010000 Y
070 L020000 Y
070 M010000 Y
070 M020000 Y
070 N010000 Y
070 N020000 N
070 O010000 Y
070 O020000 N
070 P010000 N
070 P020000 N
070 Q010000 N
070 Q020000 N
<PAGE> PAGE 7
070 R010000 Y
070 R020000 N
071 A000000 405008
071 B000000 408973
071 C000000 848238
071 D000000 48
072 A000000 6
072 B000000 41332
072 C000000 3311
072 D000000 0
072 E000000 0
072 F000000 5061
072 G000000 0
072 H000000 0
072 I000000 19
072 J000000 15
072 K000000 0
072 L000000 0
072 M000000 4
072 N000000 0
072 O000000 0
072 P000000 0
072 Q000000 0
072 R000000 14
072 S000000 1
072 T000000 0
072 U000000 0
072 V000000 151
072 W000000 22
072 X000000 5287
072 Y000000 0
072 Z000000 39356
072AA000000 4435
072BB000000 0
072CC010000 0
072CC020000 7320
072DD010000 42574
072DD020000 0
072EE000000 0
073 A010000 0.6000
073 A020000 0.0000
073 B000000 0.0000
073 C000000 0.0000
074 A000000 0
074 B000000 23633
074 C000000 0
074 D000000 807690
074 E000000 42061
074 F000000 894
074 G000000 0
074 H000000 0
<PAGE> PAGE 8
074 I000000 3722
074 J000000 741
074 K000000 0
074 L000000 17779
074 M000000 0
074 N000000 896520
074 O000000 4438
074 P000000 0
074 Q000000 0
074 R010000 0
074 R020000 0
074 R030000 0
074 R040000 3285
074 S000000 0
074 T000000 888797
074 U010000 72017
074 U020000 0
074 V010000 12.34
074 V020000 0.00
074 W000000 0.0000
074 X000000 0
074 Y000000 11502
075 A000000 0
075 B000000 882558
076 000000 11.88
077 A000000 Y
077 O000000 Y
078 000000 N
080 A000000 ICI MUTUAL INSURANCE COMPANY
080 C000000 78275
081 A000000 Y
081 B000000 127
082 A000000 N
082 B000000 0
083 A000000 N
083 B000000 0
084 A000000 N
084 B000000 0
085 A000000 Y
085 B000000 N
086 A010000 69858
086 A020000 870757
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
<PAGE> PAGE 9
086 F020000 0
087 A010000 HIGH INCOME OPPORTUNITY FUND INC
087 A020000 42967Q105
087 A030000 HIO
088 A000000 N
088 B000000 N
088 C000000 N
088 D000000 N
SIGNATURE THOMAS M. REYNOLDS
TITLE CONTROLLER
[ARTICLE] 6
[CIK] 0000910068
[NAME] HIGH INCOME OPPORTUNITY FUND INC.
<TABLE>
<S> <C>
[PERIOD-TYPE] 6-MOS
[FISCAL-YEAR-END] SEP-30-1998
[PERIOD-END] MAR-31-1998
[INVESTMENTS-AT-COST] 828,579,857
[INVESTMENTS-AT-VALUE] 877,999,973
[RECEIVABLES] 18,519,886
[ASSETS-OTHER] 0
[OTHER-ITEMS-ASSETS] 0
[TOTAL-ASSETS] 896,519,859
[PAYABLE-FOR-SECURITIES] 4,438,253
[SENIOR-LONG-TERM-DEBT] 0
[OTHER-ITEMS-LIABILITIES] 3,284,892
[TOTAL-LIABILITIES] 7,723,145
[SENIOR-EQUITY] 0
[PAID-IN-CAPITAL-COMMON] 898,243,038
[SHARES-COMMON-STOCK] 72,016,610
[SHARES-COMMON-PRIOR] 71,020,622
[ACCUMULATED-NII-CURRENT] 0
[OVERDISTRIBUTION-NII] 364,297
[ACCUMULATED-NET-GAINS] 0
[OVERDISTRIBUTION-GAINS] 58,724,201
[ACCUM-APPREC-OR-DEPREC] 49,642,174
[NET-ASSETS] 888,796,714
[DIVIDEND-INCOME] 3,310,986
[INTEREST-INCOME] 41,332,459
[OTHER-INCOME] 44,643,445
[EXPENSES-NET] 5,287,146
[NET-INVESTMENT-INCOME] 39,356,299
[REALIZED-GAINS-CURRENT] 4,434,522
[APPREC-INCREASE-CURRENT] 7,230,293
[NET-CHANGE-FROM-OPS] 36,470,528
[EQUALIZATION] 0
[DISTRIBUTIONS-OF-INCOME] 42,574,158
[DISTRIBUTIONS-OF-GAINS] 0
[DISTRIBUTIONS-OTHER] 0
[NUMBER-OF-SHARES-SOLD] 0
[NUMBER-OF-SHARES-REDEEMED] 0
[SHARES-REINVESTED] 12,211,727
[NET-CHANGE-IN-ASSETS] 6,108,097
[ACCUMULATED-NII-PRIOR] 2,386,575
[ACCUMULATED-GAINS-PRIOR] 0
[OVERDISTRIB-NII-PRIOR] 0
[OVERDIST-NET-GAINS-PRIOR] 62,691,736
[GROSS-ADVISORY-FEES] 5,060,661
[INTEREST-EXPENSE] 0
[GROSS-EXPENSE] 5,287,146
[AVERAGE-NET-ASSETS] 882,558,208
[PER-SHARE-NAV-BEGIN] 12.43
[PER-SHARE-NII] 00.56
[PER-SHARE-GAIN-APPREC] 00.05
[PER-SHARE-DIVIDEND] 00.60
[PER-SHARE-DISTRIBUTIONS] 00.00
[RETURNS-OF-CAPITAL] 00.00
[PER-SHARE-NAV-END] 12.34
[EXPENSE-RATIO] 01.20
[AVG-DEBT-OUTSTANDING] 0
[AVG-DEBT-PER-SHARE] 0
</TABLE>
