The widespread use of highly active antiretroviral therapy (HAART) since 1996 has led to a substantial decline in morbidity and mortality in patients infected with HIV, although its effect on the incidence of HIV-associated malignancies is unknown. We retrospectively reviewed the annual number of outpatient visits to our HIV clinic, inpatient admissions for HIV disease, and first admissions for patients with cancer and HIV disease at our center between 1990 and 1997. Between 1990 and 1995, there was a progressive increase in the annual number of admissions for HIV disease and HIV-associated cancers that paralleled the increasing HIV clinic volume. In 1997, however, the annual number of first admissions for Kaposi's sarcoma (KS) and non-Hodgkin's lymphoma compared with 1995 decreased by 36% and 63%, respectively, despite a continued increase in the annual number of HIV clinic visits. Similar declines were also noted in the number of new cases of biopsy-confirmed KS and primary central nervous system (CNS) lymphoma. In contrast, there was no decrease in the number of first admissions for patients with HIV infection and other cancers not typically associated with HIV infection. These findings suggest a declining incidence of HIV-associated malignancies since the introduction of HAART.