Purpose: Sex education in China has been promoted for many years, but limited data are available regarding the sources from which adolescents receive sex-related knowledge. The present study was designed to examine the sources from which Chinese adolescents obtain their information on puberty, sexuality and STI/HIV/AIDS, and whether there are any differences in sources of sex knowledge according to adolescents' demographic characteristics and sexual status. Design/methodology/approach: The data were collected in 2001 in Changchun City, China. Unmarried adolescents 15-19 years of age (322 males and 360 females) were included in a cross-sectional survey using self-administered questionnaires. Findings: Schoolteachers and mass media were identified as the two most important sources of sex knowledge. Sources of sex knowledge among adolescents on various topics (puberty, sexuality, and STI/HIV/AIDS) differed by the level of taboo associated with these topics in Chinese culture. The percentage of adolescents obtaining knowledge for puberty, sexuality, and STI/HIV/AIDS from teachers declined by topic (45.4, 30.7 and 18.4 percent, respectively), while the percentage of adolescents obtaining knowledge from television/movie increased by topic (6.7, 12.2 and 27.5 percent, respectively). Adolescents obtained knowledge on topics with less taboo (e.g. puberty) from teachers and obtained knowledge on topics with more taboo (e.g. sexuality, STI/HIV/AIDS) from mass media. However, this differs by having been sexually experienced or not. Parents were the primary source for sex knowledge on less taboo subjects. Doctors were the primary source for STI/HIV/AIDS knowledge. Sexually active adolescents obtained sex knowledge mainly from peers or mass media, while those adolescents who were not sexually experienced identified teachers and parents as the main sources of sex knowledge. Originality/value: The current study illustrates that it is necessary to improve and enhance current sex education programs in China by recognizing and strengthening the role of parents, teachers, and health care professionals in adolescent sex education. (Contains 4 tables and 1 figure.)