This article examines the characteristics of 150 children who were admitted to Brisbane hospitals with head injuries that were caused by bicycle riding. These children constitute over 20% of all the children with head injuries who were admitted to hospital; accidents involving bicycle riding are the second largest single cause of head injury in these children, after falls. There was one death in the group, and three children were moderately disabled nine months after the injury. These four children all had Glasgow coma scores of less than 9 on their admission to hospital. Only two of the 150 children wore helmets. A survey of a random subgroup of children who had sustained head injuries confirmed our opinion that many children owned helmets but did not wear them for fear of peer derision. It is suggested that this refusal can be overcome by a combination of legislative enforcement, helmet design and promotion.