BACKGROUND: Gender differences in the risk of AIDS-defining illness (ADI) and mortality have been reported in the HIV-1-infected (HIV-positive) population, with conflicting findings. We aimed to assess the impact of gender on the risk of ADI and death in HIV-positive patients infected sexually. METHODS: This was a population-based, nationwide cohort study of incident Danish HIV-positive individuals infected by sexual contact. Outcomes were progression to AIDS and death. We used Cox proportional hazards models and Poisson regression analyses to calculate the risk of progression to AIDS and mortality rate ratios (MRR) between risk groups and compared these with the general Danish population. RESULTS: We identified 587 heterosexually infected women, 583 men who have sex with women (MSW), and 1089 men who have sex with men (MSM). The total follow-up time was 13,708 person-y. At the time of HIV diagnosis MSM had a lower prevalence of AIDS compared to MSW. Women and MSW presented more often with tuberculosis and less often with AIDS-defining cancers compared to MSM. In the adjusted analyses we observed no differences in progression to AIDS. In the adjusted analyses of risk of death, there were no differences between the 3 risk groups, although we saw a trend towards a higher risk of death in older MSW. MSM had a lower risk of death compared to the background population than women and MSW. CONCLUSIONS: In the Danish HIV population, gender has no major impact on progression to AIDS or mortality. Differences in these factors between women, MSW, and MSM are mainly due to confounding from race and CD4 + cell count at diagnosis.