The purpose of this study was to determine the prevalence of back pain in school children and the role of several contributing factors; 1178 school children of both sexes answered a previously validated questionnaire. The cumulative prevalence of back pain was 51.2%. Lumbar and leg pain, and thoracic pain were more common. After multivariate analysis, five qualitative variables were correlated with back pain with a statistical, significant positive correlation with age, previous back injury, volley-ball, female sex and time spent watching television.