Racial/ethnic differences in prevalence and patterns of oral and anal sex were analyzed among girls participating in a microbicide acceptability study.Cross-sectional analysisRecruitment to participate in a 6-month study examining microbicide acceptability was conducted at a school-based health clinic and local colleges in Galveston, Texas and through snowball sampling.Sexually experienced girls (n = 202) ages 14 to 21 years of age.Girls reported on their demographic and sexual history at the intake interview.Their mean age was 18.2 years; 26% were white, 43% African-American, and 31% Hispanic. African-American girls were significantly less likely than whites and Hispanics to have had oral sex; no differences were found for anal sex. African-American girls were significantly older than whites and Hispanics when they initiated oral sex. African-American girls had a greater difference between ages of vaginal and oral sex initiation than whites and Hispanics. Oral sex history was associated with a 6-factor increase and anal sex history was associated with a 3-factor increase in the likelihood of a history of sexually transmitted infection. Future studies should explore these differences in greater depth in order to develop culturally specific STI prevention efforts.