The study aims were to evaluate the prevalence and predictors of sexual risk behaviors and urethral sexually transmitted disease (STD) among males entering care for HIV infection and to examine if sildenafil prescriptions are associated with potentially transmitting sexual risk behavior (PTSRB). The research design included (1) self-administered questionnaire of symptoms of sexually transmitted infection (STI), number of recent sex partners, unprotected sexual risk behaviors, use of drugs/alcohol during sex, and HIV disclosure; (2) urine gonorrhea/chlamydia polymerase chain reaction (PCR); and (3) record review for sildenafil prescriptions. A PTSRB was defined as insertive anal, vaginal, or oral sex without a condom. Between March 2001 and March 2002, 413 entrants were surveyed. The prevalence of positive urine PCR among those with and without urethral symptoms was 16.7% and 2.4%, respectively. Fifty-one percent met criteria for PTSRB during the preceding month. Those reporting PTSRB were more likely to report multiple partners. In a multiple logistic regression model, the following were significant (p < 0.05) predictors of PTSRB: drug or alcohol use during sex; white race; only male partners, and sildenafil use. Drug use during sex was associated both with more sex partners and more sexual risk behaviors. Always disclosing HIV status was associated with fewer partners. There was a high prevalence of PTSRB among HIV-infected males entering care. Men who have sex with men (MSM), white race, drug/alcohol use during sex, and sildenafil use were independent risk factors. PTSRB was associated with having multiple partners. Physicians should discuss risk behaviors before prescribing sildenafil.