Fifteen cases of surgically proved isodense subdural hematoma on CT were studied in the Hanyang University Hospital from Feb. 1979 to Aug. 1981. The medical recoreds and CT films were reviewed. The results were as follows; 1. The age distribution is broad from 12 years to 73 years old. The peak age incidence is in the 6thdecade. The most of the cases were male. 2. 12 out of 15 cases were conscious at the time of CT examination, andthe rest of them were stuporous or unconscious. 3. 10 out of 15 cases had historys of head injury. In 6 cases the intervals between head injury and CT examination were more than 3 weeks. 4. Skull radiograms showed a fracture inthe right frontal bone in 1 case. 5. In computed tomograms shifting of mil-line structures were observed in 14 outof 15 cases, compression and local deformities of the ipsilateral lateral ventricles in 14 cases, dilatations ofthe contralateral lateral ventricles in 14 cases, unilateral effacement of the cortical sulci in 14 cases.