To delineate the relationship between adherence to human immunodeficiency virus (HIV) therapy and sexual behavior among HIV type 1-infected women in the United States, data were collected from October 1998 through March 1999 from 766 HIV-positive women on adherence to therapy, risk behavior, and disease markers. Adherence rates of >/=95% were reported by 66% of the patients. In multivariate analyses, patients with lower rates of adherence tended to be younger (odds ratio [OR], 1.69), to be active drug users (OR, 2.27), to have detectable virus load levels (OR, 2.00), and to have a lower quality of life (OR, 1.20). Among sexually active women, lower adherence rates were associated with an increased risk for inconsistent condom use (adjusted OR, 2.17). Although counseling regarding sexual behavior and adherence to treatment regimens are often addressed separately, our data highlight the importance of discussing these factors in relation to one another, particularly with regard to patients experiencing virologic failure.