Fifteen children with an untreated posterior dislocation of the elbow were seen between 1965 and 1980. Three had a useful range of painless flexion and were not treated by operation. Twelve had a stiff elbow and had an open reduction between three weeks and three years after injury. The triceps was lengthened when it prevented reduction and Kirschner wires were used when necessary to stabilize the elbow. Complications included a transient paralysis of the hand in one patient and myositis ossificans with a rigid elbow in another. The length of follow-up ranged from one to six years. In eleven patients the average range of flexion was increased fourfold, and in all children the elbow had a useful range through 90 degrees of flexion. Eleven children said that the function of the arm was improved. However, four of them had been operated on within six weeks of the accident and might have regained a functional range of movement with a short trial of conservative therapy. We now recommend an interval of conservative treatment for children who are seen three weeks to two months after injury.