Abstract: Objective To understand the situation of adolescent-parental communication about sex and its influencing factors in Shang hai so as to provide scientific information on how parents involve well in adolescent reproductive health education.Methods 3 067 middle school students in a district of Shanghai were investig ated with self-administered questionnaire anonymously.Results About 60% and 30% adolescents felt difficult to communicate about sex ual topics with their fathers and mothers respectively.A bout 70% of the adolescents reported that they never asked their fathers questions about sex or their fathers never talked sex-related issues to them actively,and about 45% of the adolescents repor ted such situation between them and their mothers.As to the topics they talked,changes in puberty and relationship with opposite sex came to the first.Senior high school students felt more difficult to communicate with their parents than junior high school students.Mo thers talked more to their teens than fathers and were more likely to talk to daug hters than sons,while fathers were more likely to talk to sons than daughters.Parents with higher education level,better relationship with children and happier environment of family were more likely to communicate about sex with their adolescents.Conclusion The cur rent situation of the adolescent-parental communication about sex was far from the satisfactory.It was necessary to strengthen the educat ion for parents and adolescents,and improving parents.capacity for communication and enforcing their respo nsibility of sex education should be emphasized.