A retrospective study of 44 patients with osteogenesis imperfecta treated over a 14-year period was undertaken to determine the frequency and pattern of non-unions of long bones in these patients. Nine non-unions were encountered in eight patients. Four of these non-unions developed at sites of osteotomies performed at the time of intramedullary rodding. These children have remained asymptomatic, however, without appreciable limitations in spite of the non-union. Five atrophic or gap non-unions that occurred in the humerus were following inadequately treated fractures. These children were disabled on account of the non-unions. In three patients all attempts at obtaining union failed. The other two patients were braced. We conclude that non-union in osteogenesis imperfecta is not a very rare phenomenon. We also recommend that all fractures in children with osteogenesis imperfecta must be treated with appropriate immobilization to prevent a gap non-union developing, since gap non-unions are exceedingly difficult to treat.