The shape of the standard Ender nail may result in malunion in external rotation in intertrochanteric fractures treated with this device. The nail is curved in one plane, and is usually introduced into the femur without making allowance for the bowing of the diaphysis and the anteversion present in the neck. We have measured radiographically the anteversion of the femoral neck in three groups of patients after operation using Ender nails, and also assessed the anteversion of the unoperated hip for comparison. In Group I normal Ender nails were used. The operated hip showed an average of 12 degrees of retroversion compared with the opposite side. In Group II the nails were bent anteriorly at their upper end, but an average retroversion of 14 degrees was produced compared with the other hip. In Group III the nails were bent to produce anterior bowing as well as proximal anteversion. The group showed retroversion of only 1 degree compared with the normal side. We therefore recommend that Ender nails be bent in this manner in order to reduce rotatory malunion when used for intertrochanteric fractures of the neck of the femur.