Sex education is considered as one of the main aspect of education that overlook in Iran. There were many challenges against application of sex education programs. We used systematic review for answering three questions related to definition and conceptualization of sex education, sex education curriculum and skills and investigating the effectiveness of these programs. Findings of this study showed that sex education programs ranged from instruction for sexual protection to applying ethical methods for obtaining sexual health. Primary definitions of sex education were general and behavioral but as the time passed, this definition transform to culture-dependent definitions. Sex education program is effective for reducing unwanted pregnancy in adolescents and protecting from sexual abuse. It could conclude that adopting a holistic sexuality education that is characterized by applying psychological skill training methods and involvement of parents and school authorities, could fulfill the goals of sex education programs. Any sex education programs should modified based on the individual and cultural aspects to reach better success in guaranteeing sexual health for children.