The characteristics of acquired immunodeficiency syndrome-associated non-Hodgkin's lymphoma in 84 patients diagnosed and treated at San Francisco General Hospital are presented herein. While the majority were high-grade B-cell lymphomas, one cutaneous T-cell and one peripheral T-cell lymphoma were observed. In addition, three other tumors were suspicious for T-cell lymphoma. Sixty-seven percent of patients had stage IV disease, often at unusual sites. Epstein-Barr virus DNA sequences were identified in only five of 15 tumors by dot-blot analysis. Patients were treated with a variety of standard chemotherapeutic regimens, with radiation therapy alone, or with a novel chemotherapy protocol (COMET-A). No significant differences in complete response rates were observed. The most important predictor of survival was the total number of CD4-positive lymphocytes. Other predictors of survival included history of a diagnosis of acquired immunodeficiency syndrome, Karnofsky performance score, and the presence of extranodal disease. Survival was shorter among patients who received higher doses of cyclophosphamide (greater than 1 g/m2), including those treated with the COMET-A regimen. Implications for therapeutic decision making are discussed.