Objectives: To evaluate the treatment outcomes in non-gastric and non-nodal mucose-associated lymphoid tissue (MALT) lymphoma patients treated by definitive radiation therapy (RT). Methods: A total of 134 patients were analyzed. The RT dose was 30.6 or 36 Gy. Results: The median follow-up duration for all patients was 51.1 months (range, 3.0–132.4 months). Among the 88 orbital MALT lymphoma patients, 12 had disease recurrence. There were 23 head and neck tumor patients. Two patients experienced relapse, all at out-of-field locations. Gastrointestinal MALT lymphoma was diagnosed in 13 patients, and three showed local (n = 1), distant (n = 1), or local/distant (n = 1) relapse. Conclusion: RT alone is highly effective in achieving local control and long-term survival in localized MALT lymphoma. In orbital MALT, excellent local control is achieved, and relapse is predominantly observed in the contralateral eye. Other head and neck lymphomas are also well controlled.