DISEASE CHARACTERISTICS: Histologically proven relapsed or refractory, low-grade, follicular, or transformed B-cell non-Hodgkin's lymphoma (NHL) Prior rituximab allowed if no response achieved CD20-positive B-cells in lymph nodes or bone marrow required for small lymphocytic or transformed NHL Less than 25% of bone marrow cellularity in lymphoma cells No impaired bone marrow reserve, as indicated by one or more of the following: Prior myeloablative therapy with bone marrow transplantation or peripheral blood stem cell rescue Platelet count less than 100,000/mm3 Hypocellular bone marrow (no more than 15% cellularity) Marked reduction in bone marrow precursors of one or more cell lines (granulocytic, megakaryocytic, or erythroid) History of failed stem cell collection Not eligible for any active ibritumomab tiuxetan investigative protocols No CNS lymphoma, AIDS-related lymphoma, or chronic lymphocytic leukemia No pleural effusion A new classification scheme for adult non-Hodgkin's lymphoma has been adopted by PDQ. The terminology of "indolent" or "aggressive" lymphoma will replace the former terminology of "low", "intermediate", or "high" grade lymphoma. However, this protocol uses the former terminology.