The incidence and pattern of fractures in children who had been abused were compared with those of fractures sustained by children of similar ages in whom abuse had been excluded. From 1976 to 1982 there were 35 children with fractures resulting from child abuse, and all were aged under 5. Of the 826 children in the control group, seen from January to June 1981, 85% were aged over 5. Abused children were much more likely to have multiple fractures (p less than 0.001) and bruising of the head and neck (p less than 0.001). Fractures of the ribs were common in children who had been abused, and their presence, in the absence of major chest trauma, strongly suggested that abuse was occurring. Injuries to the long bones were invariably spiral or oblique fractures or subperiosteal new bone formation--both "gripping or twisting" injuries. Spiral fracture of the humeral shaft was significantly more common (p less than 0.001) in the group of abused children. Classic metaphyseal chip fractures were uncommon. One child in eight aged under 18 months who sustains a fracture may be a victim of child abuse.