Inclusion Criteria:

- Histologically confirmed, newly diagnosed or relapsed MALT, marginal zone lymphoma,
or low-grade B cell lymphoproliferative disorder which is CD5-, CD10- and CD20+

- Pathology must be reviewed at Brigham & Women's Hospital, Massachusetts General
Hospital, or the University of Rochester James P. Wilmot Cancer Center prior to
enrollment

- Documentation of CD20+ status

- Must not be a candidate for local radiotherapy with curative intent

- If gastric MALT, not a candidate for antibiotic therapy with curative intent

- Patients with leukemic phase marginal zone lymphoma are eligible if their absolute
lymphocyte count is >10,000 / µl

- Prior treatment with rituximab is permitted, if rituximab induced an objective
response which persisted for at least 6 months

- Prior radiotherapy is acceptable

- Measurable disease

- ANC: > 1000/mm3

- Platelets: > 100,000/mm3

- Hemoglobin: > 7 gm/dL

- Adequate renal function as indicated by serum creatinine <= 2 mg/dL.

- Adequate liver function, as indicated by serum total bilirubin <= 2 mg/dL.

- AST or ALT <3x Upper Limit of Normal unless related to primary disease.

- Men and women of reproductive potential must agree to use an acceptable method of
birth control during study treatment and for six months after completion of study
treatment.

- WHO Performance status
- Subject has provided written informed consent.

Exclusion Criteria:

- Patients with Waldenstrom's Macroglobulinemia or lymphoplasmacytic lymphoma are
excluded

- History of HIV

- Active infection

- Known CNS disease

- Pregnant (a negative serum pregnancy test should be performed for all women of
childbearing potential within 7 days of treatment) or currently lactating women

- Prior treatment within the last three weeks

- Prior fludarabine

- Positive direct antiglobulin test