<Page>
EXHIBIT 99.CERT
EXHIBIT 11(a)(2)
CERTIFICATIONS
I, Michael A. Pignataro, certify that:
1. I have reviewed this report on Form N-CSR of Credit Suisse
Institutional Fixed Income Fund, Inc.;
2. Based on my knowledge, this report does not contain any untrue
statement of a material fact or omit to state a material fact necessary to make
the statements made, in light of the circumstances under which such statements
were made, not misleading with respect to the period covered by this report;
3. Based on my knowledge, the financial statements, and other
financial information included in this report, fairly present in all material
respects the financial condition, results of operations, changes in net assets,
and cash flows (if the financial statements are required to include a statement
of cash flows) of the registrant as of, and for, the periods presented in this
report;
4. The registrant's other certifying officer(s) and I are
responsible for establishing and maintaining disclosure controls and procedures
(as defined in Rule 30a-3(c) under the Investment Company Act of 1940) for the
registrant and have:
(a) Designed such disclosure controls and procedures, or caused such
disclosure controls and procedures to be designed under our supervision, to
ensure that material information relating to the registrant, including its
consolidated subsidiaries, is made known to us by others within those entities,
particularly during the period in which this report is being prepared;
(b) Evaluated the effectiveness of the registrant's disclosure
controls and procedures and presented in this report our conclusions about the
effectiveness of the disclosure controls and procedures, as of a date within 90
days prior to the filing date of this report based on such evaluation; and
(c) Disclosed in this report any change in the registrant's internal
control over financial reporting that occurred during the registrant's most
recent fiscal half-year (the registrant's second fiscal half-year in the case of
an annual report) that has materially affected, or is reasonably likely to
materially affect, the registrant's internal control over financial reporting;
and
5. The registrant's other certifying officer(s) and I have disclosed
to the registrant's auditors and the audit committee of the registrant's board
of directors (or persons performing the equivalent functions):
1
<Page>
(a) All significant deficiencies and material weaknesses in the
design or operation of internal control over financial reporting which are
reasonably likely to adversely affect the registrant's ability to record,
process, summarize, and report financial information; and
(b) Any fraud, whether or not material, that involves management or
other employees who have a significant role in the registrant's internal control
over financial reporting.
Date: November 4, 2004
/s/ Michael A. Pignataro
- ------------------------
Michael A. Pignataro
Chief Financial Officer
I, Michael E. Kenneally, certify that:
1. I have reviewed this report on Form N-CSR of Credit Suisse
Institutional Fixed Income Fund, Inc.;
2. Based on my knowledge, this report does not contain any untrue
statement of a material fact or omit to state a material fact necessary to make
the statements made, in light of the circumstances under which such statements
were made, not misleading with respect to the period covered by this report;
3. Based on my knowledge, the financial statements, and other financial
information included in this report, fairly present in all material respects the
financial condition, results of operations, changes in net assets, and cash
flows (if the financial statements are required to include a statement of cash
flows) of the registrant as of, and for, the periods presented in this report;
4. The registrant's other certifying officer(s) and I are responsible for
establishing and maintaining disclosure controls and procedures (as defined in
Rule 30a-3(c) under the Investment Company Act of 1940) for the registrant and
have:
(a) Designed such disclosure controls and procedures, or caused such
disclosure controls and procedures to be designed under our supervision, to
ensure that material information relating to the registrant, including its
consolidated subsidiaries, is made known to us by others within those entities,
particularly during the period in which this report is being prepared;
(b) Evaluated the effectiveness of the registrant's disclosure controls
and procedures and presented in this report our conclusions about the
effectiveness of the disclosure controls and
2
<Page>
procedures, as of a date within 90 days prior to the filing date of this report
based on such evaluation; and
(c) Disclosed in this report any change in the registrant's internal
control over financial reporting that occurred during the registrant's most
recent fiscal half-year (the registrant's second fiscal half-year in the case of
an annual report) that has materially affected. or is reasonably likely to
materially affect, the registrant's internal control over financial reporting;
and
5. The registrant's other certifying officer(s) and I have disclosed to
the registrant's auditors and the audit committee of the registrant's board of
directors (or persons performing the equivalent functions):
(a) All significant deficiencies and material weaknesses in the design or
operation of internal control over financial reporting which are reasonably
likely to adversely affect the registrant's ability to record, process,
summarize, and report financial data information; and
(b) Any fraud, whether or not material, that involves management or other
employees who have a significant role in the registrant's internal control over
financial reporting.
Date: November 4, 2004
/s/ Michael E. Kenneally
- ------------------------
Michael E. Kenneally
Chief Executive Officer
3