In twenty-five patients, the Pavlik harness failed to obtain or maintain reduction in thirty of thirty-five congenital dislocations of the hip. All of the patients had met the clinical criteria for use of the harness in our institution: they were less than seven months old, the femoral head pointed to the triradiate cartilage on anteroposterior radiographs that were made with the child wearing the harness, and they had no evidence of neuromuscular disease or teratological dislocation. These patients were compared with seventy-one patients (eighty-one dislocations) who had also been treated with the Pavlik harness and in whom a stable reduction was obtained and maintained. Statistically significant risk factors for failure of the harness included an absent Ortolani sign at the initial evaluation, bilateral dislocation, and an age of more than seven weeks before treatment with the harness was begun. All thirty hips in which the harness failed to obtain or maintain reduction had a subsequent attempt at closed reduction after preliminary Bryant traction. Fifteen of these hips were successfully reduced closed, but two later redislocated and needed an open reduction. The remaining fifteen hips needed an open reduction, and two redislocated and needed a second open reduction.