Inclusion Criteria:

- Histologically confirmed T NHL, excluding T prolymphocytic leukemia, T lymphoblastic
lymphoma, and T/NK large granular lymphocytic leukemia.

- Measurable disease, defined as at least one bidimensionally measurable site of
disease measuring at least 1.5cm in greatest diameter.

- Failed at least one systemic chemotherapy or biologic therapy for T cell lymphoma
unless it can be clearly documented that the patient can not tolerate such therapy.

- 18 years of age or older

- Life expectancy of greater than 3 months

- ECOG Performance Status of lesser then or equal to 2

- Normal organ and marrow function as outlined in the protocol

- Agree to the use of adequate contraception prior to study entry and for the duration
of the study

Exclusion Criteria:

- Chemotherapy or radiotherapy within 4 weeks prior to entering the study

- Receiving any other study agents

- CNS lymphoma requiring active therapy

- History of allergic reactions attributed to compounds of similar chemical or biologic
composition to imatinib mesylate

- Participants requiring concomitant administration of any medications or substances
that are inhibitors or inducers of CYP3A4 are ineligible

- Patient previously received radiotherapy to 25% or greater of the bone marrow

- Uncontrolled intercurrent illness including but not limited to ongoing or active
infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac
arrhythmia, or psychiatric illness/social situations that would limit compliance with
study requirements

- Pregnant or lactating women

- History of a different malignancy except for individuals who have been disease-free
for at least 5 years and are deemed by the investigator to be at low risk for
recurrence of that malignancy

- HIV-positive individuals on combination antiretroviral therapy

- Known chronic liver disease

- Major surgery within 2 weeks prior to study entry