The objectives of this systematic review were to examine age dependency of headache prevalence in school age children and to assess secular trends of headache prevalence in the last decade, gender and regional differences. A literature search was performed in MEDLINE to identify all prevalence studies in children and adolescents. Five hundred seventy studies were found, of which 37 studies could be included for this review. Headache prevalence in school children increases with their age as demonstrated in cohorts of identical children and cross-sectional surveys covering different age groups of children in one population. Regarding a potential general increase in the prevalence of headache in children and adolescents in the last decade, there are four studies which all show some increase of headache prevalence; however, the degree of increase is varying. Prevalence of headache in girls appears to be higher than in boys. There were no clear regional differences in the prevalence of headache.