The clinical course of 54 patients with small lymphocytic lymphoma (SL) was reviewed. The majority of patients had disseminated lymphoma at the time of diagnosis; 14 patients (26%) presented with Ann Arbor stage I and II disease. Five- and 10-year survival for all patients was 76% and 49%. The only clinicopathologic features identified that predicted a shortened survival were the presence or absence of systemic (B) symptoms (15% v 63% at 10 years, P = .01) and a diffuse rather than pseudofollicular nodal architecture (47% v 87% at 10 years, P = .04). Initial bone marrow involvement was not an adverse prognostic factor for patients who presented with stage III and IV disease. Ten patients developed a marked lymphocytosis consistent with progression to a leukemic phase (chronic lymphocytic leukemia [CLL]). These ten patients had a median initial lymphocyte count of 2,790, compared with 1,580 for those patients who did not progress to CLL (P = .0001). Developing CLL did not adversely affect survival (P = .48). Thirty-seven patients were treated with various combinations of radiation and chemotherapy; 17 patients received no initial therapy. Ten-year freedom from relapse (FFR) for stage I and II patients treated with irradiation was 80% and 62%; FFR for stage III and IV treated patients was 11%. Despite the marked differences in FFR, no statistically significant difference in survival could be demonstrated between the various stages. Selected patients with advanced SL received no initial therapy; these patients had a 10-year survival that was not statistically different from the immediately treated stage III and IV patients. Patients with stage I and II SL should be treated with irradiation; prolonged FFR and possibly cure of the disease can be achieved in these patients.