The primary purpose of this study is to find out if motexafin gadolinium may be an effective treatment for patients with non-Hodgkin's lymphoma (NHL). Secondly, the safety and side effects of motexafin gadolinium will be evaluated.

Inclusion Criteria:

• ≥ 18 years old
• Refractory or relapsed indolent NHL. Eligible WHO histologies include follicular NHL (Grades 1, 2, and 3); marginal zone nodal; marginal zone splenic; and mucosa-associated lymphoid tissue (MALT) types
• Failed ≥ 1 previous regimens, one of which must have contained rituximab as either a single agent or in combination with chemotherapy
• ECOG performance status score either 0 or 1
• Willing and able to provide written informed consent

Exclusion Criteria:

Laboratory values of:

• Platelet count < 50,000/µL
• AST or ALT > 2 x the upper limit of normal (ULN)
• Total bilirubin > 2 x ULN
• Creatinine > 2.0 mg/dL

and

• Greater than three prior regimens (where a regimen is defined as a treatment for NHL given after disease progression)
• Uncontrolled hypertension
• Known history of porphyria, G6PD deficiency, HIV