Objectives: The aim of the study was to determine the prevalence of smoking among children and adolescents aged 7-18 years, and also to determine the relationship between this addiction and the Body Mass Index (BMI). Methods: Basic anthropometric measurements were performed, and information concerning cigarette smoking and basic SES was gathered using the questionnaire method. Results: More than 5% of boys admit to smoking at the age of 10-11 years, and as many as 22% 18-year-olds admit to doing so. With regard to girls, the situation is slightly better because it is only among 14-year-olds that the percentage of smokers exceeds 5%. Smoking may affect average BMIs. Smoking had a negative impact on the magnitude of physical development indices among children between 8 and 12 years old. Conclusions: The percentage of smokers increases with age. Boys smoke more often than girls. Tobacco smoking in middle childhood (8-12 years) is associated with lower BMIs.