A retrospective analysis of 144 patients with stage I-II non-Hodgkin's lymphoma (NHL) treated between June 1968 and December 1980 was performed. Patients were staged by bone marrow biopsy, chest radiography, blood chemistries, and either bipedal lymphangiography, computerized axial tomography, or surgical exploration of the abdomen. Patients were subclassified by extent of disease; minimal disease was defined as less than 10 cm and involved one or two contiguous sites, while patients with disease exceeding these limitations were considered to have extended stage I-II disease. Treatment consisted of radiation therapy (RT) alone in 74 patients and 70 patients were treated with chemotherapy with or without RT. Combination chemotherapy in patients with diffuse undifferentiated (DU) or diffuse histiocytic (DH) lymphoma resulted in a significantly higher 6-year survival as compared to patients treated with RT alone. For minimal disease DU/DH patients, the 6-year survival with chemotherapy +/- RT was 96% as compared to 61% with RT alone (P = .03). For extended disease DU/DH patients the 6-year survival with chemotherapy +/- RT was 56% as compared with 18% with RT alone (P = .003). This survival advantage from the initial use of chemotherapy was not seen in any of the other histologic subgroups.