The authors studied all patients with serologic evidence of human immunodeficiency virus (HIV) infection and malignant non-Hodgkin's lymphoma (NHL) that presented at a single hospital from 1982 to 1989. Sixteen patients were identified, all white homosexual men with a mean age of 38.2 years. Lymphoma was the initial presentation of HIV infection in 37.5%. Sixty-two percent of the cases had a high-grade NHL, 31% had intermediate-grade, and 6% (one patient) had a low-grade lymphoplasmacytoid lymphoma. Extranodal involvement was present in 43.7%, with the gastrointestinal tract and liver being the most common sites. Actuarial survival was increased by treatment with methotrexate, doxorubicin, cyclophosphamide, vincristine, prednisone, and bleomycin (MACOP-B). Colorimetric in situ hybridization identified Epstein-Barr virus (EBV) in nine of the 14 cases hybridized. A statistically significant association of EBV with diffuse small noncleaved type (i.e., Burkitt's-like) (six of six) compared with other morphologic types (three of eight) was found (P = 0.025).