The purpose of our study was to update the safety and efficacy results of radioimmunotherapy in relapsed or resistant indolent or transformed non-Hodgkin lymphoma. Methods: More than 9 y ago, we treated 12 indolent and 4 transformed, relapsed or refractory lymphoma patients with a single administration of nonmyeloablative therapy with tositumomab and I-131-tositumomab. The 16 patients had a mean of 3.1 (range, 1-6) previous chemotherapy and antibody treatments. Results: Six of 12 relapsed indolent lymphoma patients remain disease-free a mean of 9.8 y (range, 8.6-10.7 y) after radioimmunotherapy. Three of 4 transformed lymphoma patients progressed after radioimmunotherapy, and 1 patient had a partial response of 10 mo. Conclusion: Optimal patient benefit might be obtained in indolent lymphoma when administering radioimmunotherapy up-front in combination with chemotherapy and rituximab treatment. However, these results show that radioimmunotherapy alone achieved long-lasting remissions in 6 of 12 (50%) indolent lymphoma patients in relapse after 1 or multiple chemotherapies.