We found that over a 36-month period, the frequency of HIVrisk behaviors inThai MSMenrolled inthe BMCSdeclined. The odds for UAI, recreational drug use, and having more than four sexual partners in the past four months decreased by 2, 1, and 1 %, respectively, for each additional four-month visit study participants attended. However, throughout the study period only one-quarter of the participants reported maintaining consistently safe behaviors for unprotected anal intercourse, and one-third having fewer than four sexual partners during the four months preceding their visit.