The authors feel that, in the past, the angle of anteversion of the neck of the femur has been considered to be greater than it normally is. This study has shown that 25 per cent. of all adult femora will normally have anteversion of between 5 and 10 degrees, and that 66 per cent. will fall between 0 and 15 degrees. The authors believe that any angle of anteversion in the adult femur that is greater than 10 degrees is approaching the abnormal, and that anything over 15 degrees is definitely pathological. There are many differences between the male and female types of femur. Although the difference in the angle of anteversion is small, it should be considered as one of the characteristics of each type,—the female type showing a slightly greater amount of anteversion than the male type. This study bears out the facts that the infant femur has a high degree of anteversion normally (this averaged 24.4 degrees); and that, during childhood and adolescence, it gradually recedes to that seen in the adult. A reverse angle or angle of retroversion is a rather frequent finding, and its occurrence in the adult is nearly as common as the finding of an abnormal amount of anteversion.