We report a series of 50 patients under 70 years of age who had an ununited femoral neck fracture treated by a Pauwels abduction osteotomy. At an average follow-up of 7.1 years, seven patients had required prosthetic replacement and 37 others were reviewed in detail. In these patients the Harris hip score averaged 91. Twenty-two hips showed radiographic evidence of avascular femoral head necrosis, but only three of these had been replaced. For active patients with non-union of a femoral neck fracture, Pauwels osteotomy provides a high proportion of good results even in the presence of avascular necrosis of the head, providing there has been no collapse. If osteotomy fails, prosthetic replacement is still possible.