The purpose of our study was to identify the types and rates of cancers seen in high-risk human immunodeficiency virus (HIV)-infected and HIV-uninfected women. From 1993 to 1995, 1,310 women enrolled at four urban U.S. research sites in the HIV Epidemiology Research Study and were interviewed biannually to identify interval diagnoses and hospitalizations until study closure in March 2000. Cancer incidence data were collected through abstraction of medical records and death certificates. Of 871 HIV-infected and 439 HIV-uninfected women, 85% had a history of smoking and 50% a history of injection drug use. For our analysis, 4,180 person-years were contributed by HIV-infected women, and 2,308 person-years by HIV-uninfected women. HIV-infected women had 8 non-Hodgkin's lymphomas, 5 invasive cervical cancers (ICC), 1 Kaposi's sarcoma and 12 non-AIDS defining cancers, including 4 lung cancers, compared with 4 cancers in HIV-uninfected women including 1 lung cancer (all cancers, 6.22/1000 person-years vs. 1.73/1000 person-years, p β«Ψβ¬ 0.01). CD4Ψ cell counts were above 200/mm 3 in all women with ICC. HIV-infected women with lung cancer were young smokers (mean age, 40 years), and all died within 6 months of diagnosis. Lung cancer occurred at twice the rate in HIVinfected vs. uninfected women in the cohort and severalfold above expected in age-and race-matched women in U.S. national data (incidence relative risk 6.39; 95% confidence interval 3.71, 11.02; p < 10 Ψ7 ). The frequent occurrence of cervical and lung cancers have important implications for the counseling (cigarette cessation), screening (PAP smears) and care of women with HIV infection, as they live longer because of current antiretroviral therapies.