Objective:To assess the association between obesity and primary headaches in children and adolescents.Methods and Procedures:In a prospective study, the short-questionnaire version based on existing International Headache Society diagnostic criteria was administered. Two hundred and seventy-three children and adolescents (61 females) aged 9-17 years were assessed. One hundred and sixteen (42.5) subjects were of normal weight, 45 (16.5) were at risk for overweight (BMI >85th and <95th percentile for age and gender) and 112 (41) were overweight (BMI 95th percentile). The outcome measures were prevalence of headaches, type of headaches, association between headaches and elevated blood pressure in overweight subjects.Results:Headache was reported in 39 (14.3) subjects, with a similar rate in females (14.5) and males (14). Among 39 subjects with headaches, 20 (17.9) were overweight, 7 (15.6) were at risk for overweight and 12 (10.3) were normal-weight children. Among females, 7.7 of normal-weight group suffered from headaches, compared with 14.8 of the at risk for overweight group and 20.3 of the overweight group (P for trend 0.04). Among males, the occurrence of headaches was similar in all three weight groups (P 0.96). The occurrence of headaches increased from 10.6 among children aged 9-11 years to 21.8 in the 15-18 years age group (P < 0.05). In multivariate analysis, a significant independent risk for headaches was present in overweight females (odds ratio (OR) 3.93, 95 confidence interval (CI) 1.28-12.1) and in adolescents aged 15-18 years (OR 2.62, 95 CI 1.07-6.45).Elevated blood pressure was not independently associated with headaches. Of the 15 children with migraine, 12 were either at risk for overweight or overweight.Discussion: Overweight females had an almost fourfold excess risk of headaches when compared with normal-weight girls.