Over time, the epidemiologic and demographic characteristics of AIDS have changed in the United States, while the use of highly active antiretroviral therapy has changed the natural history of the disease. The goal of the study was to ascertain any changes in the epidemiologic, immunologic, pathologic, or clinical characteristics of AIDS-related lymphoma (ARL) over the course of the AIDS epidemic. Records of 369 patients with ARL diagnosed or treated at a single institution from 1982 through 1998 were reviewed. Single institutional data were compared to population-based data from the County of Los Angeles. Significant changes in the demographic profile of patients with newly diagnosed ARL have occurred, with the later time intervals associated with a higher prevalence in women (P =.25), in Latino/Hispanic individuals (P <.0001), and in those who acquired human immunodeficiency virus (HIV) heterosexually (P =.01). These changes were similar in both countywide, population-based analyses and in those from the single institution. The median CD4(+) lymphocyte count at lymphoma diagnosis has decreased significantly over the years, from 177/dL in the earliest time period (1982-1986), to 53/dL in the last time period from 1995 to 1998 (P =.0006). The pathologic spectrum of disease has also changed, with a decrease in the prevalence of small noncleaved lymphoma (P =.0005) and an increase in diffuse large cell lymphoma (P <.0001). Despite changes in the use of antiretroviral or chemotherapy regimens, the median survival has not significantly changed.