To evaluate the effect of some environmental factors on smoking, and to assess some health hazards of smoking in adolescents, this cross-sectional study was performed among 1950 students, agesll-18, selected by multi-stage random sampling from three cities in Iran. According to self-administered questionnaires, 12.9% of boys and 4% of girls reported to be smoker (OR = 3.34, 95% CI: 2.33, 4.77, p < 0.001). The mean values of total- and LDL-cholesterol were higher in smokers and their HDL-C was lower than non-smokers (163.33 +/- 33.83, 90.73 +/- 31 and 46.7 +/- 12.24 vs. 156 +/- 29.53, 85 +/- 26.5 and 49.4 +/- 13.7 mg/dl, respectively, p < 0.05). The mean systolic and diastolic blood pressures were higher in smokers than non-smokers (110.7 +/- 14.5, 67.6 +/- 11.55 vs. 104.9 +/- 14.3, 63.2 +/- 10.8 mmHg, respectively, p < 0.05). The smokers had higher BMI than non-smokers (20.34 +/- 3.84 vs. 19.55 +/- 3.66, p < 0.05). The mean food consumption frequency was lower for fruits and vegetables and higher for fat/salty snacks and fast foods in smokers than non-smokers. Logistic regression analysis showed significant association between sex, age, the number of family members and number of smokers in the family and smoking in students. The findings of this study have implications for future tobacco prevention strategies through community-based interventions.