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<PAGE> PAGE 20
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<PAGE> PAGE 21
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<PAGE> PAGE 22
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<PAGE> PAGE 23
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<PAGE> PAGE 24
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<PAGE> PAGE 25
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<PAGE> PAGE 26
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<PAGE> PAGE 27
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<PAGE> PAGE 28
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<PAGE> PAGE 29
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<PAGE> PAGE 30
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<PAGE> PAGE 31
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<PAGE> PAGE 32
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<PAGE> PAGE 33
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<PAGE> PAGE 34
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<PAGE> PAGE 35
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<PAGE> PAGE 36
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<PAGE> PAGE 37
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<PAGE> PAGE 38
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<PAGE> PAGE 39
SIGNATURE STEPHEN MEYER
TITLE CONTROLLER
<TABLE> <S> <C>
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<CIK> 0000804239
<NAME> SEI INSTITUTIONAL MANAGED TRUST
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<PAID-IN-CAPITAL-COMMON> 393628
<SHARES-COMMON-STOCK> 29055
<SHARES-COMMON-PRIOR> 18555
<ACCUMULATED-NII-CURRENT> 0
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<ACCUMULATED-NET-GAINS> 16455
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 151575
<NET-ASSETS> 563616
<DIVIDEND-INCOME> 566
<INTEREST-INCOME> 1516
<OTHER-INCOME> 0
<EXPENSES-NET> (4544)
<NET-INVESTMENT-INCOME> (2462)
<REALIZED-GAINS-CURRENT> 17612
<APPREC-INCREASE-CURRENT> 74705
<NET-CHANGE-FROM-OPS> 89855
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> (74231)
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 15890
<NUMBER-OF-SHARES-REDEEMED> (8530)
<SHARES-REINVESTED> 3140
<NET-CHANGE-IN-ASSETS> 181265
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 73427
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 2675
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 4544
<AVERAGE-NET-ASSETS> 409778
<PER-SHARE-NAV-BEGIN> 20.51
<PER-SHARE-NII> .02
<PER-SHARE-GAIN-APPREC> 2.64
<PER-SHARE-DIVIDEND> 0
<PER-SHARE-DISTRIBUTIONS> (3.85)
<RETURNS-OF-CAPITAL> 0
<PER-SHARE-NAV-END> 19.32
<EXPENSE-RATIO> 1.10
<AVG-DEBT-OUTSTANDING> 0
<AVG-DEBT-PER-SHARE> 0
</TABLE>
<TABLE> <S> <C>
<ARTICLE> 6
<CIK> 0000804239
<NAME> SEI INSTITUTIONAL MANAGED TRUST
<SERIES>
<NUMBER> 112
<NAME> SMALL CAP GROWTH CLASS D
<MULTIPLIER> 1,000
<S> <C>
<PERIOD-TYPE> YEAR
<FISCAL-YEAR-END> SEP-30-1997
<PERIOD-START> OCT-01-1996
<PERIOD-END> SEP-30-1997
<INVESTMENTS-AT-COST> 416265
<INVESTMENTS-AT-VALUE> 567785
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<TOTAL-ASSETS> 567785
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<TOTAL-LIABILITIES> 4169
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 1958
<SHARES-COMMON-STOCK> 116
<SHARES-COMMON-PRIOR> 90
<ACCUMULATED-NII-CURRENT> 0
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 16455
<OVERDISTRIBUTION-GAINS> 0
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<NET-ASSETS> 563616
<DIVIDEND-INCOME> 566
<INTEREST-INCOME> 1516
<OTHER-INCOME> 0
<EXPENSES-NET> (4544)
<NET-INVESTMENT-INCOME> (2462)
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<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> (355)
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 33
<NUMBER-OF-SHARES-REDEEMED> (30)
<SHARES-REINVESTED> 23
<NET-CHANGE-IN-ASSETS> 181265
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<ACCUMULATED-GAINS-PRIOR> 73427
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<OVERDIST-NET-GAINS-PRIOR> 0
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<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 4544
<AVERAGE-NET-ASSETS> 1823
<PER-SHARE-NAV-BEGIN> 20.29
<PER-SHARE-NII> (.11)
<PER-SHARE-GAIN-APPREC> 2.66
<PER-SHARE-DIVIDEND> 0
<PER-SHARE-DISTRIBUTIONS> (3.85)
<RETURNS-OF-CAPITAL> 0
<PER-SHARE-NAV-END> 18.99
<EXPENSE-RATIO> 1.46
<AVG-DEBT-OUTSTANDING> 0
<AVG-DEBT-PER-SHARE> 0
</TABLE>
<TABLE> <S> <C>
<ARTICLE> 6
<CIK> 0000804239
<NAME> SEI INSTITUTIONAL MANAGED TRUST
<SERIES>
<NUMBER> 121
<NAME> MID CAP
<MULTIPLIER> 1,000
<S> <C>
<PERIOD-TYPE> YEAR
<FISCAL-YEAR-END> SEP-30-1997
<PERIOD-START> OCT-01-1996
<PERIOD-END> SEP-30-1997
<INVESTMENTS-AT-COST> 27148
<INVESTMENTS-AT-VALUE> 35069
<RECEIVABLES> 0
<ASSETS-OTHER> 0
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 35069
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 22
<TOTAL-LIABILITIES> 22
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 22156
<SHARES-COMMON-STOCK> 1792
<SHARES-COMMON-PRIOR> 1668
<ACCUMULATED-NII-CURRENT> 40
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 4930
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 7921
<NET-ASSETS> 35047
<DIVIDEND-INCOME> 427
<INTEREST-INCOME> 66
<OTHER-INCOME> 0
<EXPENSES-NET> (267)
<NET-INVESTMENT-INCOME> 226
<REALIZED-GAINS-CURRENT> 5433
<APPREC-INCREASE-CURRENT> 4865
<NET-CHANGE-FROM-OPS> 10524
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> (243)
<DISTRIBUTIONS-OF-GAINS> (2094)
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 918
<NUMBER-OF-SHARES-REDEEMED> (900)
<SHARES-REINVESTED> 106
<NET-CHANGE-IN-ASSETS> 10093
<ACCUMULATED-NII-PRIOR> 67
<ACCUMULATED-GAINS-PRIOR> 1581
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 115
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 271
<AVERAGE-NET-ASSETS> 28695
<PER-SHARE-NAV-BEGIN> 14.96
<PER-SHARE-NII> .13
<PER-SHARE-GAIN-APPREC> 5.86
<PER-SHARE-DIVIDEND> (.14)
<PER-SHARE-DISTRIBUTIONS> (1.25)
<RETURNS-OF-CAPITAL> 0
<PER-SHARE-NAV-END> 19.56
<EXPENSE-RATIO> .93
<AVG-DEBT-OUTSTANDING> 0
<AVG-DEBT-PER-SHARE> 0
</TABLE>
November 25, 1997
To the Shareholders and
Board of Directors of
SEI Institutional Managed Trust
In planning and performing our audit of the financial statements
of SEI Institutional Managed Trust (the "Trust") for the year ended
September 30, 1997, we considered its internal control, including
control activities for safeguarding securities, in order to determine
our auditing procedures for the purpose of expressing our opinion on
the financial statements and to comply with the requirements of Form
N-SAR, not to provide assurance on internal control.
The management of the Trust is responsible for establishing and
maintaining internal control. In fulfilling this responsibility, estimates
and judgments by management are required to assess the expected
benefits and related costs of control activities. Generally, control
activities that are relevant to an audit pertain to the entity's objective
of preparing financial statements for external purposes that are fairly
presented in conformity with generally accepted accounting principles.
Those control activities include the safeguarding of assets against
unauthorized acquisition, use or disposition.
Because of inherent limitations in internal control, errors or irregularities
may occur and not be detected. Also, projection of any evaluation of
internal control to future periods is subject to the risk that it may become
inadequate because of changes in conditions or that the effectiveness of
the design and operation may deteriorate.
Our consideration of internal control would not necessarily disclose
all matters in internal control that might be material weaknesses under
standards established by the American Institute of Certified Public
Accountants. A material weakness is a condition in which the design
or operation of any specific internal control components does not
reduce to a relatively low level the risk that errors or irregularities in
amounts that would be material in relation to the financial statements
being audited may occur and not be detected within a timely period
by employees in the normal course of performing their assigned
functions. However, we noted no matters involving internal
control, including control activities for safeguarding securities,
that we consider to be material weaknesses as defined above as
of September 30, 1997.
This report is intended solely for the information and use of
management and the Securities and Exchange Commission.
