SummaryOsteotomies of the hip fixed with the Coventry lag screw were performed in 29 patients (38 hips) from May 1976 to June 1981. The ages of the children ranged from 24 months to 15 years, with an average of 7.3 years. There were 15 boys and 14 girls. Follow-up averaged 24 months, with a range of 11 to 67 months, and all patients were followed to union. The osteotomies were most commonly indicated for hip deformities associated with cerebral palsy, congenital deformities of the hip, congenital dislocation of the hip, neuromuscular abnormalities, post-traumatic deformities, and other miscellaneous conditions. Results were analyzed according to the bone disorder. All of the osteotomies united, averaging 10.5 weeks to union. Complications included one nonunion which required grafting before the osteotomy united, and two malunions. Following union, there was one fracture distal to the plate, and subcutaneous prominence of the screw developed in three patients. The Coventry lag screw is technically easy to use, is tolerated well, and produced satisfactory fixation in the majority of the patients in this study.