RESUMEN
Present study has been conducted with the purpose of determining substance abuse style for street children in Tehran. 576 street children of 10-19 years were evaluated. Data were gathered by demographic and substance use check list. Theses check lists were designed by the researchers and included some simple question about type and duration of substance use. Several psychiatrist confirmed the content of check list. 36.7% of the children had lifetime smoking of cigarette. The frequency of smoking in boys was significantly higher than girls [P<0.05]. The mean age of the girls with smoking habit was significantly lower than the boys [P<0.05]. It should be noted that street children are at high risk group for using tobacco. Theses children are also exposed to the dangerous behaviors and sexually transmitted diseases