To determine what side effects and what clinical effect, if any, the administration of this investigational product, IDEC-114 in combination with Rituxan® [Rituxan® as a single agent is approved by the United States Food and Drug Administration (FDA) to treat patients with relapsed or refractory follicular NHL], has in this patient population.

Inclusion Criteria:

• Signed IRB-approved informed consent
• Greater than or equal to 18 years of age
• Proof of follicular lymphoma
• Progressive disease requiring treatment after at least 1 prior standard therapy
• Acceptable hematologic status, liver function, and renal function
• Patients of reproductive potential must agree to follow accepted birth control methods during treatment and for 3 months after completion of treatment

Exclusion Criteria:

• No response to prior Rituxan® or Rituxan®-containing regimen
• Presence of CLL or CNS lymphoma
• Known history of HIV infection or AIDS
• Prior diagnosis of aggressive NHL or mantle-cell lymphoma
• Serious nonmalignant disease
• Pregnant or currently breast feeding