The authors performed this retrospective study to further investigate the relationship between non-Hodgkin's lymphoma (NHL) and the Acquired Immunodeficiency Syndrome (AIDS). From January 1984 through December 1987 all cases of AIDS and NHL diagnosed at the University of Colorado affiliated hospitals were identified and submitted to chart review. Twenty-five patients fulfilled criteria for the diagnosis of AIDS and 24 had biopsy-proven NHL, an additional patient met criteria for the diagnosis of primary central nervous system lymphoma and was included in the analysis. All patients had known risk factors for the development of AIDS. Of the biopsy proven tumors, 23 were categorized as high grade. Most patients (68%) presented with stage IV disease and 92% with extra nodal involvement. Median survival was 5 months and the cause of death was most often progressive lymphoma and/or opportunistic infections. These data are similar to previously published series. Clinical trials to evaluate effective treatment are warranted.