The authors reviewed all cases of non-Hodgkin's lymphoma primarily involving the gastrointestinal tract treated at Memorial Hospital during the period from 1949-1978. Complete clinical records were available in 104 cases. Slides of original pathology specimens were available in 81 cases. Tumors were classified by Rappaport, Lukes-Collins and modified Kiel classifications. All patients were staged retrospectively, using modified Ann Arbor staging. The primary tumor was in the stomach in 76 patients, in the small bowel in 15 and in the large bowel in 13. The life-table survival for all patients at five years was 44% and for the 81 Stage I and II patients it was 53%. We found a trend toward improved survival for patients treated in the last decade (P = 0.05). Using Cox regression analysis, survival was found to be correlated with stage (P less than 0.0001) and involvement of adjacent structures (P = 0.007). For Stage I patients, resection and radiation therapy were equally effective alone in controlling local tumor even though factors responsible for the selection of either treatment could not be identified. For Stage II patients, resection combined with radiation therapy controlled local disease better than either treatment alone. For Stage II, patient survival was correlated with the pattern of nodal involvement (P less than 0.0001). Neither the choice of treatment (resection, radiation therapy, or resection with radiation therapy; P = 0.17) nor the involvement of resected margins (P = 0.22) affects survival. Among 81 Stage I and II patients, 68% had recurrences outside the primary field of treatment and 60% outside the abdomen. Systemic multiple modality therapy should be considered for patients at high risk for recurrence.