We tested the impact of stress management training on sexual behavior and immune functioning in 64 gay men infected with human immunodeficiency virus (HIV). Subjects randomized to the stress management group met for eight two-hour sessions and one all day retreat to learn systematic relaxation, health behavior change, and stress management skills. Compared to those randomized to a wait list control, treatment subjects reported significantly fewer sexual partners in the prior month at post-test (1.10 vs 2.29 for controls). There were no differences between groups in lymphocyte numbers and function.