The authors present their experience of the use of intertrochanteric osteotomy for the treatment of idiopathic necrosis of the head of the femur. The results obtained from 102 osteotomies performed on 81 patients with the disease are analysed. The mean follow-up is 4.2 years. The results show a statistically significant clinical improvement after operation. Patients presenting with Ficat and Arlet Stage II involvement fared much better than those with more severe changes. Better results were also seen in those with a necrosis angle of less than 200 degrees. No radiological improvement was seen although a high percentage showed no deterioration. The choice of treatment for the condition is discussed in the light of these results.