BACKGROUND: Two risk-reduction counseling sessions can prevent sexually transmitted diseases (STDs); however, return rates for test results are low. STUDY: A randomized, controlled trial compared rapid HIV testing and counseling in 1 visit with standard HIV testing and counseling in 2 visits. Main outcomes were STDs (gonorrhea, chlamydia, trichomoniasis, syphilis, HIV) within 12 months. Participants were 15- to 39-year-old STD clinic patients in Denver, Long Beach, and Newark. STD screening and questionnaires were administered every 3 months. RESULTS: Counseling was completed by 1632 of 1648 (99.0%) of the rapid-test group and 1144 of 1649 (69.4%) of the standard-test group. By 12 months, STD was acquired by 19.1% of the rapid group and 17.1% of the standard group (relative risk [RR], 1.11; confidence interval [CI], 0.96-1.29). STD incidence was higher in the rapid-test group than in the standard-test group among men (RR, 1.34; CI, 1.06-1.70), men who had sex with men (RR, 1.86; 95% CI, 0.92-3.76), and persons with no STDs at enrollment (RR, 1.21; 95% CI, 0.99-1.48). Behavior was similar in both groups. CONCLUSIONS: Counseling with either test had similar effects on STD incidence. For some persons, counseling with standard testing may be more effective than counseling with rapid testing.