Advances in antiretroviral therapy and treatment or prophylaxis against opportunistic infection have resulted in prolongation of the survival of patients with acquired immunodeficiency syndrome (AIDS). Previous research has demonstrated an association between AIDS and risk of non-Hodgkin's lymphoma (NHL). In addition to the approximately 3% of individuals found to have NHL at the time of AIDS onset, others continue to develop NHL following AIDS diagnosis. Data from the Surveillance, Epidemiology, and End Results (SEER) Program of the National Cancer Institute demonstrated a sharply increasing incidence of NHL among men in the age range 20-49 years since 1983 in the United States. Based on new data on the risk of NHL following AIDS diagnosis, on estimates of improved survival following AIDS diagnosis, and on projections of future AIDS incidence, we considered four sets of assumptions and estimated the number of AIDS-related NHL cases in 1992 to be between 2900 and 9800. Three of these projections were higher than the estimate of 4700 cases obtained by linear extrapolation of SEER incidence trends. These projections of AIDS-related NHL incidence suggest that between 8% and 27% of all NHL cases that occur in the United States in 1992 will arise as a consequence of infection with the human immunodeficiency virus (HIV), imposing a substantial health care burden. More research into the pathogenesis of lymphoma and new approaches to antiretroviral and antilymphoma therapy will be necessary to prevent and treat this formidable complication of infection with HIV.