The objective of this study was to report prevalence rates of adherence by HIV-seropositive individuals to medical recommendations for the treatment of HIV infection, a behavioral pattern referred to as AIDS secondary prevention. We report cross-sectional data (n = 2,593) from two household-based and two bar-based samples of gay/bisexual men, gathered in 1992 in Tucson, Arizona, and Portland, Oregon. The main outcome variables were prevalence of HIV antibody testing and adherence to recommended secondary prevention behaviors to prevent onset of AIDS symptoms. Approximately one-third of the gay/bisexual men in these samples do not know their current HIV status. Of the gay/bisexual men who do know that they are HIV-seropositive, approximately three-fourths adhere to each of the secondary prevention recommendations, as appropriate to their stage of disease progression. In a multivariate logistic model, three variables distinguished between HIV-seropositive men who did and did not adhere: perceived antiviral treatment norms (OR = 1.4, CI = 1.1-1.7), perceived efficacy of secondary prevention treatments (OR = 1.4, CI = 1.1-1.7), and quality of the relationship with one's health-care provider (OR = 2.5, CI = 1.6-4.0). These findings indicate that efforts to support AIDS secondary prevention behaviors can occur not only through health education to change the perceptions of at-risk communities about the options available to delay the onset of opportunistic infections among HIV-seropositive individuals but also by enhancing effective doctor/patient communication.