Inclusion Criteria:

- For the Phase I portion of the study, patients must have pathologically confirmed
diagnosis of low-grade or follicular, CD20-positive, B-cell, non-Hodgkin's lymphoma
that has relapsed or is refractory. For the Phase II portion of the study, patients
must have a pathologically confirmed diagnosis of low-grade or follicular,
CD20-positive, B-cell, non-Hodgkin's lymphoma (Follicular, predominantly small
cleaved or follicular, mixed small cleaved and large cell, International Working
Formulation classification B or C or REAL classification follicular center grade 1,2)
that has relapsed or is refractory.

- Previously treated with at least one anti-cancer regimen for NHL

- Measurable disease (lesions that can be accurately measured in 2 dimensions by CT
scan with a greatest transverse diameter of >/= to 2cm or palpable lesions with both
diameters of 2cm or more)

- Life expectancy of at least 12 weeks

- WHO performance status or 0 or 1

- Adequate marrow and organ function (as defined in the protocol)

- Completed major surgery, radiotherapy, chemotherapy, immunotherapy or
biotherapy/targeted therapies at least 4 weeks prior to study entry (6 weeks if
treated with a nitrosourea or mitomycin). Patients must have recovered from all
prior treatment toxicity to Grade 1 or less, exclusive of alopecia.

Exclusion Criteria:

- Prior combination therapy with rituximab and CAMPATH; prior therapy with either agent
alone is permitted

- A history of a T-cell lymphoma

- Known AIDS-related HIV-positive lymphoma

- For the Phase II portion of the study (once MTD has been determined), bulky disease,
ie, any single mass >10cm or circulating malignant cells of 25,000/uL or more

- Prior autologous bone marrow or stem cell transplant within 6 months of study entry

- Prior allogeneic bone marrow transplant or organ transplant

- Prior radiotherapy to the only site of measurable disease

- Medical condition requiring chronic use of oral, high-dose corticosteroids

- Use of investigational agents within 30 days of study enrollment

- Past history of anaphylaxis following exposure to humanized monoclonal antibodies

- Known, active, infection, including HIV positive

- Diagnosis of another malignancy within the previous five (5) years, unless the
probability of recurrence of the prior malignancy is < 5%. Patients with curatively
treated early stage squamous cell carcinoma of the skin, basal cell carcinoma of the
skin, cervical intraepithelial neoplasia (CIN), and patients with a history of
malignant tumor in the past that have been disease-free for at least 5 years

- Active central nervous system (CNS) involvement with lymphoma

- Pregnant or nursing women

- Any significant concurrent disease or illness that would, in the opinion of the
investigator, compromise patient safety or compliance, or interfere with the
interpretation of study results

- Active hepatitis or a history of prior viral hepatitis B or C, or positive hepatitis
B serologies without prior immunization