Two hundred and seventy-eight patients with malignant lymphomas seen in the Department of Radiation Therapy at the Yale-New Haven Hospital during the years 1958-1966 were studied. Of 142 patients with Hodgkin's disease, 79 had Stage I or II disease, 54 of whom received radical radiation therapy (tumor doses in excess of 3,000 rads to all known disease with intent to cure). The cumulative survival rate of those radically treated was 82 per cent at 5 years counting all patients and 55 per cent including only those living and free of disease. Stage I and II patients not radically treated had a cumulative survival rate of 35 per cent at 5 years but no survivor was free of disease. Reactivations occurred in 55 per cent of patients with Hodgkin's disease but usually consisted of extensions to immediately adjacent lymph node areas. Sixteen such extensions in 9 patients were successfully treated. Local control of disease was achieved in approximately 75 per cent of fields treated with doses greater than 3,000 rads. Fields receiving 2,000-3,000 rads were controlled only 45 per cent of the time. Of 136 patients with lymphosarcoma, reticulum cell sarcoma and follicular lymphoma, 36 had Stage I and II disease, 20 of whom received radical radiation therapy. Seven of 12 Stage I patients survived free of disease for periods of 3 to 8 years. No Stage II patient survived. In contrast to Hodgkin's disease, the other lymphomas tend to be more generalized when first seen and usually disseminate rather than spread in a contiguous manner. If confined to one anatomic area, however, they appear to be curable with radical radiation therapy.