Inclusion Criteria:

1. Must sign an informed consent form.

2. Age ≥ 18 years

3. Must be able to adhere to the study visit schedule and other protocol requirements.

4. Must have a documented diagnosis of B-cell CLL.

5. Must have been treated with a purine analog- or bendamustine- containing regimen in
the first and/or second line induction therapy. Alemtuzumab-containing regimens in
place of purine analog- or bendamustine- containing regimens will also be allowed for
those patients with 17p deletion.

6. Must have achieved a minimum of partial response following completion of second-line
induction therapy.

7. Must have an Eastern Cooperative Oncology Group (ECOG) performance status score of
≤2.

8. Must agree to follow pregnancy precautions as required by the protocol.

9. Must agree to receive counseling related to teratogenic and other risks of
lenalidomide.

10. Must agree not to donate blood, eggs or sperm as defined by the protocol

Exclusion Criteria:

1. Any medical condition, that would prevent the subject from signing the informed
consent form.

2. Active infections requiring systemic antibiotics.

3. Systemic infection that has not resolved > 2 months prior to initiating lenalidomide

4. Autologous or allogeneic bone marrow transplant as second line therapy.

5. Pregnant or lactating females.

6. Participation in any clinical study or having taken any investigational therapy
within 28 days.

7. Known presence of alcohol and/or drug abuse.

8. Central nervous system (CNS) involvement.

9. Prior history of malignancies, other than CLL, unless the subject has been free of
the disease for ≥3 years. Exceptions include the following:

- Basal cell carcinoma of the skin

- Squamous cell carcinoma of the skin

- Carcinoma in situ of the cervix

- Carcinoma in situ of the breast

- Incidental histologic finding of prostate cancer (TNM stage of T1a or T1b)

10. History of renal failure requiring dialysis.

11. Know Human Immunodeficiency Virus (HIV), active Hepatitis B Virus (HBV) and/or active
Hepatitis C Virus (HCV) infection.

12. Prior therapy with lenalidomide.

13. Presence of specific hematology and/or chemistry abnormalities

14. Severe rash due to prior thalidomide treatment

15. Uncontrolled hyperthyroidism or hypothyroidism

16. Venous thromboembolism within one year

17. ≥ Grade-2 neuropathy

18. Uncontrolled autoimmune hemolytic anemia or thrombocytopenia