In a cross-sectional analysis, we investigated frequency of sexual activity and factors associated with risky sexual behavior among 624 older men, aged 49−80, with or at risk for HIV infection. During the prior 6 months, 75% reported sexual activity with at least one partner, and one quarter of both the HIV-negative and HIV-positive men had more than one sexual partner. Only 18% of the HIVnegative men and 58% of the HIV-positive men always used condoms with their sexual partners. Factors independently and positively associated with risky sexual behavior included lack of HIV infection, any drug use in the past 6 months, greater importance of sex in one's life, weekly or more frequent sexual activity in the past 6 months, and ever taking sildenafil. These results suggest that older men with or at risk for HIV infection are sexually active, participate in risky sexual behavior, and need safer sex interventions.