The health needs of adolescent sex workers are many, yet this population is rarely included in health assessments resulting in scarce information available about their issues. This study examined the sociodemographic and health-risk behavior factors of street-based adolescent sex workers and the prevalence of sexually transmitted infections (STI) in this population. Experienced outreach workers were responsible for recruiting participants and obtaining informed consent. Personal interviews with street-based female adolescent sex workers were conducted to collect sociodemographic, and health-risk behavior information. Counseling sessions regarding STI prevention were provided. Medical personnel were responsible for the collection of blood and cultures for STI tests. Results indicate that these youth are more likely to have STI if they are using drugs or are depressed. These findings suggest the need to effectively link preventive measures for substance abuse and depression to the treatment of STI. Other implications for reaching adolescent sex workers are discussed.