A cross-sectional study on tobacco smoking prevalence and related socio-psychological parameters in Moscow school students aged 10-17 was performed. Data from an anonymous self-report (n = 4802) on smoking prevalence was confirmed by special technique--expert assessment. Widespread smoking was found: among male 5th graders (the youngest group) 14.4% are smokers (those who smoked at least 1 cigarette over the past 3 months); among male 10th graders (oldest group) 53.2% smoke; among females these figures were 0.8% for the youngest students and 28.2% for the oldest ones. A significant difference in awareness of smoking health hazards and attitudes towards the habit was shown among school students with various smoking statuses. Complaints about cough and shortness of breath after light physical stress were significantly more prevalent in regular smokers as compared to non-smokers. The possible causal role of some psychological factors in early formation of smoking habit is discussed.