The research means to know the relation between islamic sex education and sexual behavior in youth. The research location is chosen purposively in Depok district, Sleman regence. Research subjects are also chosen purposively. Based on that technique, can be collected 200 research subjects. Data gathered through sending scaled questionnaires and analyzed through spearman's product moment correlation. The research result found that there is a significant negative correlation between islamic sexual education and sexual behavior in youth. That means that the higher islamic sex education received, the lower sexual behavior done by youth. Based on the research result, it is recommended that the ministry of social affairs through the directory of family empowerment should keep educating youth to prevent free sexual behavior. To the parents should consistently apply sex education according to sharia (islamic norm) as early as possible in coincidence with children to adult growth. To youth should join positive and benefit activity in their lives, away from youth free sexual behavior.