We estimated the prevalence of Chlamydia trachomatis and Neisseria gonorrhoeae genital tract infections among 302 Montreal street youth (223 boys) and identified associated risk factors. Study participants, 14-25 years old (average 20.9 years), meeting specific criteria for homelessness, were recruited in street youth agencies. Participation included a structured interview and provision of a urine specimen. Among sexually active youth, (n = 300) 30.0% had more than five heterosexual partners and 13.0% had at least one homosexual partner (last year), 10.7% had received money in exchange for sex (last six months) and 47.0% reported sexual relations resulting in pregnancy (lifetime). Among all youths, 82.1% had used at least one type of illicit drug, and 30.1% injected drugs at least once (last six months). The prevalence of C. trachomatis infection was 6.6% (95% CI 4.1-10.0%). Prevalence did not vary significantly by sex, age or any other variable, except history of pregnancy (10.4% among youth with history of pregnancy vs 3.6% among others, P = 0.02). No cases of N. gonorrhoeae infection were found.