We report long-term survival and prognostic factors in 252 patients with stage I high-grade lymphoma. Median patient age was 64 years and 49% of patients had extranodal lymphoma. Premenopausal women had less risk of extranodal lymphoma than older women or males (p < 0.002). Disease specific 5 and 15 years' survival in patients < 64 years was 83% and 76%, respectively; compared to 54% and 46% in patients > 64 years of age. Age, non-centroblastic histology, B-symptoms, and increased serum lactate dehydrogenase (LDH) were independently negative prognostic factors (p < 0.01), while extranodal, testicular, or bulky ( > 6 cm) lymphoma presentation were of no prognostic significance. A radiation dose of 40 Gy in 2 Gy fractions to the primary site prevented in-field relapse in 159 of 173 irradiated patients (92%) and only three of 173 patients (1.7%) had local relapse in the absence of systemic dissemination.