Objectives: This study was performed in order to evaluate the quality of health services provided to the adolescents at mobile health clinics and to improve the services for them, and to figure out knowledge level of adolescents on sex, birth control methods and artificial abortion, and the effect of the knowledge levels those items on sexual behavior. The data obtained will be utilized for sex health education program in the future. Methodology: A total of 2,021 adolescents who visited mobile sexual health clinics in Seoul, Inchon, Busan, Daejon, Cheonbuk, Kwangju and Daegu were surveyed in November 2007. The items surveyed were level of satisfaction about the services provided by mobile sexual health clinics, personal opinions and experience of artificial abortion, knowledge level about birth control, sexual experience and pregnancy. The above mentioned items were analyzed by general characteristics such as religion and geographical area. Results: The study subjects were generally satisfied with the services of mobile sexual health clinics. But they were not satisfied with the information about birth control methods provided by the clinics. The subjects who had better knowledge about sex were more satisfied with the services provided by the clinics. And the subjects who had knowledge about birth control methods but did not have birth control experience were also more satisfied with the services of clinics. The subjects who reported that artificial abortion should be allowed were also more satisfied with the services of the clinics. Experiences of sex, pregnancy, and artificial abortion were not correlated to satisfaction of the clinic services. Conclusions: The mobile sexual health clinics have to continues to provide sex health education and other sex related health services to adolescents. More practical information about birth control methods should be provided to the adolescents by the clinics based on the study results. Active preventive measures for unwanted pregnancy should be provided to the adolescents by the clinics.