One hundred and fifty bicycle accidents seen at the Children's Hospital Sheffield over a 6-month period from mid-August 1979 were analysed and 9.3 per cent of the cases were admitted. Twenty-two per cent had fractures, 20 per cent had soft tissue injuries of face or scalp, 8 children having damaged their teeth. Of the accidents 17.3 per cent were due to hitting an obstruction, 30.7 per cent were due to loss of control on a hill or corner and 8 per cent were of mechanical origin. Eighty-eight per cent had cycling experience of a year or more, and 32.7 per cent had had previous cycling accidents. Comparison with other types of accidents previously studied at the hospital, involving skateboards, playground equipment or road traffic accidents affecting child pedestrians, showed that by far the most serious were those involving child pedestrians. The injuries from bicycle accidents were similar in severity to those involving skateboards.