This is a study for the long-term follow-up of patients who completed at least two years of follow-up after treatment with Tositumomab and/or Iodine I 131 Tositumomab (BEXXAR)on Study RIT-I-000, RIT-II-001, RIT-II-002, RIT-II-004 or CP-97-012. All patients will be assessed for survival and disease status, including subsequent therapy for NHL, and for long term safety. Laboratory evaluations consisting of a TSH level (for all patients) and a complete blood cell (CBC) count with a differential and platelet count (for patients in continuing response only) will be obtained annually through Year 10 post treatment with Tositumomab and/or Iodine I 131 Tositumomab.

Patients that remain in response to their previous treatment with BEXXAR, will additionally be followed radiographically for response and progression.

Inclusion Criteria:

• Patients must have enrolled in one of the following Corixa sponsored clinical trials: RIT-I-000, RIT-II-001, RIT-II-002, RIT II-004 or CP-97-012 and are >2 years post Tositumomab and/or Iodine I 131 Tositumomab administration.
• Patients must give written informed consent by signing an IRB/ethics committee approved consent form prior to entry on this follow-up study.

Exclusion Criteria:

• Inability to meet the above referenced inclusion criteria.

The study population consists of patients with NHL previously treated at least 2 years ago with Tositumomab and/or Iodine I 131 Tositumomab on Study RIT-I-000, RIT-II-001, RIT-II-002, RIT-II-004, or CP-97-012.