28 patients were subjected to follow-up examination after having suffered for more than 10 years from idiopathic necrosis of head of femur. The high incidence of the bilateral affection of the hip joint as well as the occurrence of multiple osteonecroses are correlated with distrubances of lipid metabolism. Under conservative treatment the disease takes a progressive course, which, however, can remain subclinical for a long time. Good postoperative results can only be expected from intertrochanteric corrective osteotomy which often leads to a regeneration of the head of femur. Caution is recommended before confirming the indication for athrodesis or total endoprothesis because of the risk of disturbances of consolidation or loosening of the implant.