As part of an HIV prevention study, 15-25 year-old young men who have sex with men (YMSM) were surveyed in community settings annually from 1999 to 2002. Data are presented from six comparison communities in the study; these communities recruited Latinos (Jackson Heights, NYC; San Gabriel Valley, CA), African Americans (Atlanta, GA); Asians/Pacific Islanders (San Diego, CA); and primarily white men (Detroit, MI and Twin Cities, MN). Men were asked about unprotected anal intercourse (UAI) in the past three months with male partners. The prevalence of UAI reported in these six communities ranged 27-35% in 1999, compared with 14% to 39% in 2002. Significant reductions in UAI over time were observed in Jackson Heights and San Gabriel Valley. A quadratic trend was noted in Detroit, with a significant increase in UAI from 1999 to 2000 followed by a significant decrease in UAI from 2000 to 2002. There was a nonsignificant increase in UAI in the Twin Cities, and no significant trends in UAI in Atlanta or San Diego. Behavioral trends among YMSM vary considerably across subpopulations and highlight the necessity of local behavioral surveillance and culturally tailored prevention efforts for specific racial and ethnic groups.