Epidemiology of childhood fractures in Niigata city was longitudinally evaluated. Incidence of fracture was increased by 3.46-fold in 27 years follow-up period with the peak incidence at 14 years of age (second grade of junior high school) . Most affected site was upper extremity and main cause of fracture was sports activity. From the current study, one risk factor of the childhood fracture could be aggressive sports activity and additional effect of growth spurt and over use.