METHOD: We performed a retrospective case control study of head injury in elementary school children over a five-year period in Shimizu city. Population is 240, 000 and there are 26 elementary schools in this city. The principle of the school can decide whether helmet wearing should be a rule for pupils, which means there are only two possible situations, wearing or not wearing a helmet while walking. Elementary school children are prohibited from bicycling to school and there is no school bus system at all. The number of head injuries and other injuries were collected from the data sheet by the insurance system of the School Safety Division of the National Stadium and School Health Center of Japan.

RESULTS: There were 13 elementary schools which required students to wear a helmet while walk. One school had changed from wearing a helmet to not wearing a helmet during the 5-year period. The accumulated annual number of elementary school children was 32,922 required to wear helmets, and 56,214 not required to wear helmets. The number of injuries among children wearing helmets was 58 (0.18%), and 125 (0.22%) among children not wearing helmets during the 5-year period. Head injuries were recorded in 4 children (0.012%) wearing helmets and 10 (0.018%) who were not wearing helmets.

CONCLUSION: There was no significant difference between children wearing helmets and those not wearing helmets in the incidence of all injuries and head injuries by Xy test. The odds ratio for the no helmet system was 1.26 ( 0.92 to 1.71 for 95 % confidence) for all injuries and 1.46 ( 0.45 to 4.12 for 95 % confidence) for head injuries.