Abstract: Objective To understand the current status of knowledge, attitude and behaviors on reproductive health among the teen-agers in Shanghai. Methods During May to September 2013, the survey was conducted among 4 942 students in eight high schools, eight vocational high schools, eight middle schools and two universities in four districts in Shanghai, using stratified cluster sampling method.Results The subjects included 2 456 males and 2 486 females with an average age of (16.84±1.53). The teen-agers had a low level of knowledge on reproductive health, especially the knowledge of pregnancy and contraception, and there was significant difference in gender and age groups respectively. The attitude towards sex-related behaviors was open. The acceptance rate of premarital sexual behavior, unmarried cohabitation, premarital pregnancy, one-night stand and multiple sexual partners was 66.9%, 62.7%, 34.0%, 28.1%, and 28.1% respectively. According to multivariate logistic regression analysis, the acceptance of premarital sexual behavior was correlated to gender, education level, knowledge of condom and sexually transmitted diseases, and love behavior (P<0.05). Conclusion The teen-agers in Shanghai have poor knowledge of reproductive health and an open attitude towards sex-related behaviors. It is important to pay attention to the education and guidance of teen-agers' reproductive health knowledge, so as to help them build a complete and comprehensive system on reproductive health knowledge and skills.