Despite high rates of human immunodeficiency virus/sexually transmitted infection (HIV/STI) among commercial sex workers and international concern that male clients may constitute a critical bridge population for HIV/STI transmission, little empirical data exist within the United States to characterize men who purchase sex or to assess their sexual risk and HIV/STI infection. The study involves the analysis of a community-based survey of men aged 18-35 years attending urban health centers (n=1515) to assess the prevalence of engagement in sex purchasing during the past year and to evaluate relations with self-reported HIV/STI diagnosis and symptoms across this same period. More than 1 in 12 (8.7%) men reported exchanging drugs, money, or a place to stay for sex with a female partner in the past year. Such behavior was associated with additional sexual risk taking and emerged as an independent predictor of self-reported HIV/STI diagnosis [adjusted odds ratio (ORadj)=2.99; 95% confidence interval (CI): 1.51 to 5.94] and STI symptoms (ORadj=2.57; 95% CI: 1.57 to 4.22) in the past year in analyses adjusted for alternate HIV/STI risk sources. Sex purchasing is a common form of HIV/STI risk among the population sampled. Men engaging in such behavior are more likely to be HIV/STI infected and, thus, represent a risk to the sexual health of both commercial and noncommercial sex partners. Further research is needed to inform interventions targeted toward male clients of prostituted women.