This paper presents the results of the latest (1990) follow-up in a series of periodic surveys on the sexual behavior of Colombian university students. It documents significant gender differences in sexual practices and the decreasing albeit still important role of prostitution in the sexual lives of male students. This article also shows that, since the previous 1985 survey, there has been little change in the sexual behaviors of students potentially risky for HIV infection, and that new, more aggressive approaches to its prevention should be implemented among Colombian students and the Colombian population at large.