Inclusion Criteria:

- Age ≥ 18 years at the time of signing the informed consent form

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

- Must have a documented diagnosis of B-cell CLL

- Must be relapsed or refractory to at least 1 regimen for treatment of CLL . At least
one of the prior treatments must have included a purine analog-based or
bendamustine-based regimen

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

Exclusion Criteria:

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

- Active infections requiring systemic antibiotics

- Systemic treatment for B-cell CLL within 28 days of initiation of lenalidomide
treatment

- Alemtuzumab therapy within 120 days of initiating lenalidomide treatment

- Prior therapy with lenalidomide

- History of grade 4 rash due to prior thalidomide treatment

- Planned autologous or allogeneic bone marrow transplantation

- Central nervous system (CNS) involvement as documented by spinal fluid cytology or
imaging.

- Uncontrolled hyperthyroidism or hypothyroidism

- Venous thromboembolism within 12 months

- ≥ Grade-2 neuropathy

- Uncontrolled autoimmune hemolytic anemia or thrombocytopenia

- Disease transformation [i.e. Richter's Syndrome (lymphomas) or prolymphocytic
leukemia]

- Participation in any clinical study or having taken any investigational therapy
within 28 days prior to initiating lenalidomide therapy