Certifications

I, Charles E. Porter, a principal financial officer of
Putnam Mid Cap Fund 2000, a series of Putnam Investment
Funds, certify that:
1. I have reviewed this report on Form N-SAR of Putnam Mid
Cap Fund 2000, a series of Putnam Investment Funds;
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; and
3. Based on my knowledge, the financial information
included in this report, and the financial statements on
which the financial information is based, 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.

Date: September 27, 2002
/s/Charles E. Porter
Charles E. Porter
Treasurer and Executive Vice President


Certifications

I, Karnig H. Durgarian, principal executive officer of
Putnam Mid Cap Fund 2000, a series of Putnam Investment
Funds, certify that:
1. I have reviewed this report on Form N-SAR of Putnam Mid
Cap Fund 2000, a series of Putnam Investment Funds;
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; and
3. Based on my knowledge, the financial information
included in this report, and the financial statements on
which the financial information is based, 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.

Date: September 27, 2002
/s/Karnig H. Durgarian
Karnig H. Durgarian
Principal executive officer


Certifications

I, Steven D. Krichmar, a principal financial officer of
Putnam Mid Cap Fund 2000, a series of Putnam Investment
Funds, certify that:
1. I have reviewed this report on Form N-SAR of Putnam Mid
Cap Fund 2000, a series of Putnam Investment Funds;
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; and
3. Based on my knowledge, the financial information
included in this report, and the financial statements on
which the financial information is based, 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.

Date: September 27, 2002
/s/Steven D. Krichmar
Steven D. Krichmar
Principal financial officer