16 ischemic femoral heads from human adult were studied with radiologically and histologically. The two heads from fresh fracture of femoral neck of 1 month looked grossly normal; radiograms and CT showed no abnormality though necrosis surrounded by living bone tissue without cystic formation was found on the top area histologically. The pathology including the 12 collapsed heads from old neck fracture and 2 osteoarthritic heads were similar but varied in degree and extent of mineralization with time. Numerous cysts, were walled off by a layer of osteosclerosis on the necks side. While dense fibrovascular tissues some containing bits of dead bone trabeculae and cartilage filled certain cystic areas, empty cysts were found in 8 of the specimens. Beyond the cystic area, the bone and bone marrow adequately congested and had fairly good blood supply. Based on these findings, the authors suppose that leaking of joint fluid through fissures into deeper part of the head form cisterns which expand with increasing joint fluid pressure may be one of the causes of cyst formation. In early stage of ischemia with head in normal contour, replacement of the degenerated area with bone grafting may serve as a good choice of treatment.