Aims: The current research assessed therate of substance use among Iranian secondaryschool students. Participants: 470boy secondary school students selected randomlyand were assessed. Measurements: Aconfidential questionnaire based on DSM-IV anda prior study was distributed, completed by thestudents and collected in the same sessions in2001. Results: Their mean age was13.6 yr., (SD = 0.67) ranging from 12 to 14. Ofthe subjects 105 (22.3%) reported usage ofsubstance (s) once or more sometime duringtheir lives: tobacco 82 (17.5%) alcohol 32(6.8%), opium 3 (−0.6%), hashish 1 (−0.2%), and heroin 2 (0.4%). Only 39 (8.3%) of the students were current substance dependent: 29 (6.2%) were tobacco dependent and 13 (2.8%)were alcohol dependent. Some were using morethan one substance. Conclusions:Tobacco and alcohol were found to be the mostprevalent form of substance use. Seekingpleasure, modeling and release of tension werethe most common reasons for initial substanceuse. The most common reasons reported forcurrent use were seeking pleasure, habit andrelease of tension, respectively. Thesefindings can be implicated in planningpreventive programs. Some of the findings aredifferent from those carried in the west.Cultural attitudes could be the causes of thedifferences.