The diagnosis of the avascular necrosis of the femoral head(AVN) has advanced. RI scan, intrasseous pressure monitoring, intramedullary venography, CT, MRI and selective femoral angiography are used in diagnosis. Among these methods, selective or super selective angiography is necessary to study the change of the vessels of the hip,because the vascular insufficiency could be a major etiology of AVN. Selective femoral angiography was performedfor 23 hips of 22 patients who were suspected as AVN by simple radiographs and RI scans in order to estimate the change of vascularity of the femoral head. The results were as follow. 1. The alteration of vasculature appearedin 21 cases among all 23 caes (91%), which included 100% in the traumatic group(4/4 cases ) and 90% innontraumatic group(17/19 cases). 2. The affected vessles in nontraumatic group were the proximal portion of theposterior branch of the medical circumflex artery in 2 cases, the midportion of posterior branch in 2 cases, thedistal portion of the posterior branch in 11 cases, and superior capsular branch in 2 cases. 3. The affected vessels in traumatic group were proximal portion in 1 cases, midportion in 1 case, and superior capsular artery in2 cases. 4. The obstruction of inferior capsular artery was noted in 6 cases of nontraumatic group. 5. The retrograde filling of the posterior branch of medial circumflex artery were noted in 1 cases from superior gluteal artery, in 1 case from inferior gluteal artery, in 1 cases from superior and inferior gluteal artery and regrograde filling of inferior gluteal artery from medial circumflex artery was in 6 cases.