Compulsory Helmet Use Reduces MVA and Its Death in School Children Yoshiyuki Minowa1,2, Akiyoshi Kasii2 and Sachima Inoue3 Objective: We studied th effect of helmet use by school children on the prevention of head injuries due to motor vehicle accidents (MVA) in Omiya, a city of 440,000 located 20km north to Tokyo, Japan. Method: School reports were collected retrospectively for MVA among 200,000 students at 36 schools in Omiya city from 1989 to 1995. All schools were less than 1km from major intercity routes 16 and 17. Accident reports from 8 schools (cases) at which helmet use was compulsory when going to school were compared with 28 other schools (controls). Cases were divided into 4 with compulsory helmet use group (group C) and 4 which voluntary helmet use group (group V). Group V changed from compulsory helmet use to voluntary use in 1991. Changes in number and MVA rates were evaluated for 1989-91 and 1992-95. Results: In 36 schools, the nonfatal MVA injury rate increased from 1.0 per 1,000 pupils per year in 1989-91 to 1.4 in 1992-95 (p<0.05). Nonfatal MVA rates among group V pupils increased significantly from 0.4 in 1989-91 to 1.6 in 1992-95 (p<0.01). The rate among group C pupils decreased from 1.3 in 1989-91 to 0.4 in 1992-95. The rate among group C pupils plus group V pupils in 1989-91 was 0.7, lower than among controls plus group V in 1992-95 (p<0.05). There were 3 MVA deaths in 36 schools but no deaths in group C. Conclusion: Compulsory helmet use by student significantly reduced the rate of head injuries in nonfatal MVA and death.