In November 1983, we surveyed 655 gay men in San Francisco regarding their sexual practices during the previous month and the same month one year ago. The sample was selected to include men in situations that would lead to high risk of sexual activities related to AIDS (acquired immune deficiency syndrome) transmission (i.e., men frequenting bathhouses and gay bars) as well as men in low-risk situations (those going to neither place and men in primary relationships). The Bath group showed little change in frequency of bathhouse use and in number of sexual partners from that location. The other groups showed substantial reductions in frequency of sexual contacts from bars, baths, T-rooms, or parks. Men in monogamous relationships showed little change in sexual behavior within their relationship. Men in non-monogamous relationships and men not in relationships reported substantial reductions in high-risk sexual activity, but not a corresponding increase in low-risk sexual behavior. Knowledge of health guidelines was quite high, but this knowledge had no relation to sexual behavior. Using sex to release tension, use of sex to express gay identity, and knowledge of persons with AIDS in the advanced stages of disease were related to frequency and type of sexual behavior.