AbstractBackground:The relationship between screen time (ST) and the frequency of snack consumption in a national sample of Iranian children and adolescents was assessed. The present nationwide survey was conducted on 14,880 school students living in urban and rural areas of 30 provinces in Iran. Trained healthcare providers conducted the physical examination and completed the questionnaire of the World Health Organization – Global School-Based Student Health Survey (WHO-GSHS).Methods:The association between ST (total time spent watching TV and using a computer in leisure time) and the frequency of snack consumption was determined using ordinal logistic regression analysis. The subjects were 13,486 students out of the 14,880 invited including 50.8% boys. The mean (SD) age of participants was 12.47 (3.36) years.Results:In multivariate models, for students who had prolonged ST (more than 4 h/day), the odds of daily consumption of sweets (odds ratio, OR 1.25; 95% CI 1.14–1.4), salty snacks (OR 1.6; 95% CI 1.5–1.76), soft drinks (OR 1.52; 95% CI 1.4–1.7), canned fruit juice (OR 1.3; 95% CI 1.2–1.4), and fast food (OR 1.53; 95% CI 1.4–1.7) were higher compared to those with low ST. Furthermore, the odds of daily consumption of milk in students who had prolonged ST (more than 4 h/day) were lower compared to those with low ST (OR 0.9; 95% CI 0.8–0.99).Conclusions:Prolonged time spent watching TV and using a computer during leisure time might be associated with unhealthy dietary habits. Moreover, inactivity induced by prolonged ST may also lead to unhealthy dietary habits and in turn excess weight in children and adolescents.