Objective: Nowadays, addiction is considered one of the greatest social and economical and health problems. Undoubtedly, The Ecstasy have between some juveniles and youths. This study was performed to understand the knowledge about the Ecstasy tablets. Methods: In this descriptive-analytical study 200 students from Tehran universities and universities of medical sciences. Data collecting tool was a structured questionnaire containing 14 questions. Data was analyzed using chi square. Results: It was revealed that only 44 students had high, 55 student had moderate and 101 students had weak knowledge about Ecstasy. There was no significant relationship between knowledge score and variable such as gender, place of residence. Also, there was a significant correlations between age, marriage position , occupation and college about the Ecstasy . Conclusion: That in order to increase the knowledge leveling the students about Ecstasy, mass medias like television, newspapers, radio and university sittings.