Authors conducted a clinical study on thirty-six hips out of thirty patients which had been treated with core decompression for osteonecrosis of femoral head and followed up for more than one year (average, twenty-five months: range, one year to six years and five months). Results obtained from the study were as follows. As for Ficats staging, the thirty-six hips consisted of ten hips of Stage I, eighteen hips of Stage IIA, eight hips of Stage IIB, and none of Stage III or IV. They were treated with core decompression(8 hips) or core decompression with cancellous chip graft (28 hips) by random selection. Clinical assessment of these cases were made according to Ficats criteria(1985) and the results were: for Stage I (10 hips) five very good's two good's, three fair's and none failure's, for Stage IIA (18 hips) five very good's, six good's, five fair's and two failure's, for Stage IIB (8 hips) one very good's, four good's, one fair's and two failure's. If the cases were to be observed regradless of staging, there were eleven hips (30.5%) of very good, twelve hips (33.3%) of good, nine (25.0%) of fair and four (11.2%) of failure. X-ray asessment of the hips were also made and the results were: for Stage I (10 hips) three very goods, one good, six fairs and none faiures: for Stage IIA none very good, eight goods, eight fairs and two failures.: for Stage IIA (8 hips) none of very good and good, two fairs and six failures. There were three hips (8.4%) of very good, nine hips (25.0%) of good, sixteen hips (44.4%) of fair and eight hips (22.2%) of failure. From above results, authors were able to draw assumption that core decompression with or without cancellous chip graft is beneficial for alleviation of symptoms of osteonecrosis of femoral head for uncertain period yet if done in early stage, even though there is not any concrete evidence that it may delay or reverse the pathologic process therein.