Rotational subcapital osteotomy of the humerus for recurrent anterior dislocation of the shoulder associated with a large Hill-Sachs lesion was performed first by us in 1964 as a trial. From 1967 through 1981, 207 rotational humeral osteotomies were performed. Follow-up was possible on 180 of these shoulders. The over-all redislocation rate was 5.7 per cent and the rate of non-traumatic redislocation, 1.1 per cent. Limitation of motion of more than 10 degrees was present in only 3.9 per cent, the maximum limitation of external rotation being 15 degrees in one patient. The average loss of external rotation was less than 5 degrees, without noticeable diminution of power or function in most patients. The results as graded by a standard rating scale were good to excellent in 90 per cent, fair in 3 per cent, and poor in 7 per cent of the patients. The fair and poor results were due to redislocation, delayed union or non-union, post-traumatic arthritis, and over-rotation at the osteotomy site. Reoperation was necessary in two patients with a non-traumatic recurrence, in six patients with delayed union or non-union, and in one patient with excessive rotation at the osteotomy site. Plate removal was performed one to two years postoperatively in 107 of the 180 shoulders. Of the 321 recurrent dislocations seen over the fourteen-year period, 65 per cent were associated with a moderate to severe posterior-superior impression fracture of the humeral head (Hill-Sachs lesion).(ABSTRACT TRUNCATED AT 250 WORDS)