The purpose of this study is to evaluate prevalence and patterns of condom use among patients attending a sexually transmitted disease (STD) clinic, who are at increased risk of developing STDs. Interviews of 800 patients attending a Baltimore STD clinic were conducted. The prevalence of condom use was dependent on the measure of use employed. For example, 9 out of 10 patients reported ever having used condoms, slightly less than one-third of the patients reported having used condoms in the past 30 days, and only 17% of the patients reported using a condom at last sex. Use also varied somewhat by type of sexual partner, and within any given relationship, from first to last sexual encounter. The most significant factor corresponding to condom use in the 30 days prior to the interview was number of sexual partners (lifetime and in the last month). Multivariate analyses revealed number of lifetime partners to be the most significant predictor of condom use for men, whereas age was the most significant variable for women. These findings suggest that interventions should focus not only on the individual, but the couple. © 1992 American Sexually Transmitted Diseases Association.