According to World Health Organization (WHO) reports, 80000-100000 young adults begin to consume the narcotic substances, most of whom living in developing countries. Besides family environment, school has important role in forming the one's behaviors as the pioneer educating social environment. This study was conducted to determine the smoking pattern in Tehran students during 2008. This was a cross-sectional study with a cluster multi stage randomized sampling using the GYTS (Global Youth Tobacco Survey) and demographic questionnaires on 4523 students in Tehran. Data were analyzed using chi square test. Overall, 4523 students (50.2% boys and 49.8% girls) were studied with the mean age of 14.69±2.09 years. Totally, 25.5% of students have ever smoked cigarettes, and 54.9% ever smoked water-pipe. Most of the subjects commenced smoking when they were 14-15 years old (27.6%), while 38.8% purchased cigarette from stores or markets. Boys smoked more frequently in public places (36.6%), whereas girls experienced smoking at home (51.6%). Unfortunately, 22% of subjects smoked more than 5 cigarettes per day. Almost one in five current smokers had gave up and attempted to stop smoking and this was more pronounce among boys (p< 0.01). Our results were in agreement with most of other studies of its kind worldwide. With respect to the incidence of experience and consumption of tobacco, designing and accomplishment of preventive program with first level of approach for lower ages, and inspection and execution of tobacco sale prohibition for adolescences seem to be reasonable.