Inclusion Criteria:

• Age >/=18 years.
• Established diagnosis of B-cell CLL by NCI Working Group criteria.
• </=1 previous line of chemotherapy.
• Expected survival > 6 months.
• Acceptable hematologic status, liver function, renal function, and pulmonary function.
• Negative serum pregnancy test for both pre-menopausal women and for women who are < 2 years after the onset of menopause.
• Written informed consent.

Exclusion Criteria:

• Prior treatment with interferon, rituximab or other monoclonal antibody.
• Prior allogeneic BMT or autologous BMT or peripheral stem cell transplant (PBSCT) or patients who are considered to be candidates for allogeneic or autologous BMT or PSCT as assessed by their treating physician.
• Fertile men or women of childbearing potential not using adequate contraception.
• Severe grade 3 or 4 non-hematological toxicity or prolonged (> 2 weeks) grade 3 or 4 cytopenia on prior fludarabine or nucleoside analogue regimen.
• History of Fludarabine-induced or clinically significant autoimmune cytopenia.
• History of other malignancies within 2 years prior to study entry, except for adequately treated carcinoma in situ of the cervix; basal or squamous cell skin cancer; low grade early stage localized prostate cancer treated surgically with curative intent; good prognosis DCIS of the breast treated with lumpectomy alone with curative intent.
• Medical conditions requiring long term use (> 1 month) of systemic corticosteroids.
• Active bacterial, viral, or fungal infection requiring systemic therapy.
• Severe cardiac disease.
• Seizure disorders requiring anticonvulsant therapy.
• Severe chronic obstructive pulmonary disease with hypoxemia.
• Uncontrolled diabetes mellitus or hypertension.
• Transformation to aggressive B-cell malignancy.
• Known infection with HIV, HCV, or hepatitis B.
• Treatment with any other investigational agent, or participation in another clinical trial within 30 days prior to entering this study.
• Known hypersensitivity or anaphylactic reactions to murine antibodies or proteins.
• Any co-existing medical or psychological condition that would preclude participation in the study or compromise ability to give informed consent.