This is a multi-center study for the long-term follow-up of surviving patients who are expected to complete or who have completed at least two years of follow-up after treatment with Iodine I 131 Tositumomab (BEXXAR) on Studies CP-97-011, CP-98-025, CP-99-032, or CP-99-036. All patients will be assessed for survival and disease status, including subsequent therapy for NHL, and for long-term safety. Additionally Laboratory evaluations consisting of a TSH level and a complete blood cell (CBC) count with a differential and platelet count will be obtained annually. Additionally, patients who remain in long-term response following Iodine I 131 Tositumomab treatment will be followed for response and progression.

Inclusion Criteria:

• Patients must have enrolled in one of the following Corixa sponsored clinical trials: CP-97-011, CP-98-025, CP-99-032, or CP-99-036 and are >2 years post treatment with Iodine I 131 Tositumomab.
• 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 above referenced inclusion criteria.

The study population consists of subjects which have been previously treated with Iodine I 131 Tositumomab in Studies 104505, 93229/023, 393229/007, 104514 and 393229/028.