To establish rates of potentially risky sexual behaviors among Colombian adolescent students. A total of 230 9th and 11th graders at a Colombian high school (69% of enrolled students) were anonymously surveyed about selected reproductive health behaviors using the Centers for Disease Control and Prevention's self-administered Youth Risk Behavior Survey. The response rate was >90%. The group was demographically representative of students. Twenty-nine percent of the group had engaged in intercourse (13% of 9th and 43% of 11th graders). Male gender [beta = 0.7873; odds ratio (OR) = 2.09; 95% confidence interval (CI) = 1.57-3.08] and increasing age (beta = 0.3413; OR = 1.41; 95% CI = 1.02-1.93) were each significantly correlated with prior sexual activity. Compared with females, males initiated intercourse at a significantly earlier age (beta = 0.284; p < .001) but did not report significantly more partners (means 2.1 vs. 1.4; chi2 = 1.25; p = .262). Forty-eight percent of respondents used contraception during their last encounter. Sixty-three percent used oral contraceptives or condoms, while the remainder used less effective methods. Contraceptive use did not correlate with gender or age. Age was significantly and positively correlated with use of alcohol prior to sexual activity (B = 1.28; OR = 3.6; 95% CI = 1.49-8.44). Compared with U.S. populations of similar ages, the Colombian group surveyed had fewer sexually active members, reported fewer partners, and used contraception with lower frequency.