OBJECTIVE: To study attitudes towards and use of bicycle helmets among schoolchildren; to determine whether these attitudes are associated with the involvement of parents and school in bike safety. SETTINGS: Nine intermediate level schools and five upper level schools in two Swedish municipalities. METHOD: A survey with 1,485 participants aimed at pupils aged 12-15 years conducted during late spring 1997. Associations between parent and school involvement and children's attitudes and helmet use were studied using LisRel analyses. RESULT: At some point during their school years, a majority of the children stopped wearing bicycle helmets. Of 12-13 year olds, 80% said that they had used helmets when they were younger but at the time of the study, only 3% aged 14-15 years used helmets. Use decreased significantly during school years (p<0.001). The majority stated they quit using helmets because they were ugly, silly, uncomfortable, or inconvenient. There was a strong association between parental involvement, children's attitudes, and helmet use. However, parent involvement decreased as the children grew older. CONCLUSION: To increase the voluntary use of bicycle helmets among schoolchildren their attitudes must be influenced. An intervention aimed at both parents and children may be required.