The goal of this clinical research study is to learn if Revlimid (lenalidomide) can help to reduce the level of leukemia in your body. The safety of this drug will also be studied.

The Study Drug:

Lenalidomide is designed to change the body's immune system and may also interfere with the development of tiny blood vessels that help support tumor growth. Therefore, in theory, it may decrease or prevent the growth of cancer cells.

Study Drug Administration:

If you are found to be eligible to take part in this study, you will take lenalidomide by mouth every night each day for up to 12 months. You should swallow lenalidomide capsules whole, with water, at the same time each day. Do not break, chew, or open the capsules. If you miss a dose of lenalidomide, take it as soon as you remember on the same day. If you miss a dose, it should not be made up on another day.

The dose and schedule of lenalidomide may be changed, depending on the side effects you may experience.

Study Visits:

Once a week during the first 4 weeks, blood (about 1 tablespoon) will be drawn for routine tests. Blood may be drawn more often if the dose of lenalidomide needs to be changed or if you experience side effects.

After the first 4 weeks, blood (about 1 tablespoon) will be drawn for routine tests every 2 weeks until the doctor thinks your dose of lenalidomide will not change. After this, blood (about 1 tablespoon) will then be drawn every 4 weeks for routine tests.

On Month 4 and 12 (+14 days), you will have a physical exam and blood (about 2-3 teaspoons) will be drawn to check the status of the disease.

On Month 4 and 12 (+14 days), and then every 3 months after that (unless your study doctor does not think it is necessary), you will have a bone marrow biopsy and aspirate to check the status of the disease.

Length of Study:

You will continue receiving the study drug for up to 12 months. You will continue having study visits for as long as the disease remains stable. You will be taken off study early if the disease gets worse or intolerable side effects occur.

Inclusion Criteria:

1. Patients should have completed their chemotherapy 3 months prior to start of treatment with lenalidomide and not more than 9 months prior to treatment initiation.
2. Patients with CLL/Small Lymphocytic Lymphoma (SLL) that achieve a complete or stable partial remission after combination of chemotherapy. Patients in complete remission need to have documentation of residual disease by immunophenotyping and/or PCR molecular testing.
3. Eastern Cooperative Oncology Group (ECOG)/World Health Organization (WHO) status of 0-2.
4. Adequate renal and hepatic function (creatinine equal to or less than 2mg/dL - total bilirubin equal to or less than 2).
5. Females of childbearing potential (FCBP). A female of childbearing potential is a sexually mature woman who: 1) has not undergone a hysterectomy or bilateral oophorectomy; 2) or has not been naturally postmenopausal for at least 24 consecutive months (has NOT had menses at any time in the preceding 24 consecutive months).
6. FCBP must have a negative serum or urine pregnancy test with a sensitivity of at least 50 mIU/mL within 10-14 days prior to and again within 24 hours of starting lenalidomide and must either commit to continued abstinence from heterosexual intercourse or begin TWO acceptable methods of birth control; one highly effective and one additional effective method AT THE SAME TIME at least 28 days before starting taking lenalidomide.
7. FCBP must also agree to ongoing pregnancy testing weekly for the first four weeks and then every 28 days while on therapy and at discontinuation of treatment.
8. Men must agree to use a latex condom during sexual contact with a FCBP even if they have had a successful vasectomy. All patients must be counseled at a minimum of every 28 days about pregnancy precautions and risks of fetal exposure.
9. Age 18 and older.
10. Signed, written IRB-approved informed consent.

Exclusion Criteria:

1. Known sensitivity to lenalidomide or thalidomide or it's derivatives
2. Known positivity for HIV or active hepatitis B or C.
3. Pregnant or breast feeding females. Lactating females must agree not to breast feed while taking lenalidomide.
4. History of tuberculosis within the last five years or recent exposure to tuberculosis equal to or less than 6 months.
5. Any serious medical condition, laboratory abnormality, or psychiatric illness that would prevent the subject from signing the informed consent form.
6. 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.
7. Use of any other experimental drug or therapy within 28 days of baseline.
8. Concurrent use of other anti-cancer agents or treatments

Adverse event collection for 12 months of treatment.