A study of 436 replacements of the femoral head by Austin Moore, Thompson, Valls, and Judet prostheses, done from 1950 to 1965, revealed best results with the Austin Moore prosthesis. Only 195 patients could be followed for five years or more. The Austin Moore prosthesis gave 31 per cent excellent, 36 per cent good, 25 per cent fair, and 8 per cent poor results; relatively few patients showed much change in the results obtained—roughly as many showed long-term improvement as showed deterioration.