Inclusion Criteria:

- Understand and voluntarily sign an informed consent form.

- Age > = 18 years at the time of signing the informed consent form.

- Able to adhere to the study visit schedule and other protocol requirements.

- Histologically confirmed diagnosis of mantle cell Non-Hodgkin's Lymphoma with cyclin
D1 overexpression by immunohistochemistry, and a characteristic immunophenotypic
profile with CD5(+), CD23(-), CD20(+), and CD10(-). In tumor tissues with negative
cyclin D1, evidence of cyclin D2 or D3 overexpression by immunohistochemistry will be
acceptable.

- No prior systemic therapy for lymphoma including chemotherapy or immunotherapy.
Patients may have received involved-field radiation therapy which has been
discontinued at least 4 weeks prior to treatment in this study.

- Patient has measurable disease as defined by a tumor mass > 1.5 cm in one dimension.

- Low and intermediate-risk disease as defined by MIPI score.

- Subject who the investigator considers that chemotherapy is not indicated.

- ECOG performance status of < = 2 at study entry.

- Laboratory test results within these ranges:

- Absolute neutrophil count > = 1000 /mm³

- Platelet count > = 75,000 /mm³

- Calculated creatinine clearance ≥ 30 ml/min by Cockcroft-Gault formula • Total
bilirubin < = 2 x ULN

- AST (SGOT) and ALT (SGPT) < = 3 x ULN.

- Disease free of prior malignancies for > = 5 years with exception of currently
treated basal cell, squamous cell carcinoma of the skin, carcinoma "in situ" of the
cervix or breast, or localized prostate cancer.

- All subjects must be registered into the mandatory RevAssist® program, and be willing
and able to comply with the requirements of RevAssist®.

- Subjects of reproductive potential agree to use birth control throughout their
participation in this study, and for three months following study termination.

- Females of childbearing potential (FCBP)† must have a negative serum or urine
pregnancy test with a sensitivity of at least 50 mIU/mL within 10 - 14 days and again
within 24 hours prior to prescribing lenalidomide for Cycle 1 (prescriptions must be
filled within 7 days). FCBP must either commit to continued abstinence from
heterosexual intercourse or begin TWO acceptable methods of birth control, one highly
effective method and one additional effective method AT THE SAME TIME, at least 28
days before she starts taking lenalidomide. FCBP must also agree to ongoing
pregnancy testing. Men must agree to use a latex condom during sexual contact with a
FCBP even if they have had a successful vasectomy. See Appendix: Risks of Fetal
Exposure, Pregnancy Testing Guidelines and Acceptable Birth Control Methods.

- Able to take aspirin (81 or 325 mg) daily as prophylactic anticoagulation (patients
intolerant to ASA may use warfarin or low molecular weight heparin).

- Asymptomatic carriers of hepatitis B virus can be considered for study if they agree
to and comply with close monitoring and suppressive therapy with lamivudine during
treatment and for additional six months after coming off study.

Exclusion Criteria:

- Any serious medical condition, laboratory abnormality, or psychiatric illness that
would prevent the subject from signing the informed consent form.

- Pregnant or breast feeding females.

- Any condition, including the presence of laboratory abnormalities, which places the
subject at unacceptable risk if he/she were to participate in the study or confounds
the ability to interpret data from the study.

- Use of any other experimental drug or therapy within 28 days of baseline.

- Patient on corticosteroids within two weeks prior to study entry, except for
prednisone < = 10 mg/day or equivalent for purposes other than treating MCL.

- Known hypersensitivity to thalidomide.

- Any prior use of lenalidomide.

- Known seropositive for or active viral infection with human immunodeficiency virus
(HIV), hepatitis B virus (HBV) or hepatitis C virus (HCV). Patients who are
seropositive because of hepatitis B virus vaccine are eligible.

- Known central nervous system (CNS) involvement by lymphoma.

- Patient at high risk for deep vein thrombosis not willing to take DVT prophylaxis.

- Patient has had major surgery within the last 3 weeks