Single photon emission computed tomography(SPECT) is a kind of radioisotope scan that can display cross sectional images. It has been recently applied to the evaluation of regional cerebral blood flow in many cerebral diseases and head traumas. Technetium-99m hexamethylpropyleneamine oxime was successfully used with SPECT in 53 patient who had head injuries and were referred to Hangang Sacred Hear Hospital during 17 months from Feb. 1988 to Jun. 1989. Brain SPECT scans were done in all patients and correlated with brain CT scans. The results were as follows : 1. Twenty-five of 53 patients(47%) showed abnormal findings on SPECT ; focal brain parenchmal lesions were seen in eight, non-focal lesions in 13, and meningeal lesions in four. 2. Thirteen of 25 patients with positive SPECT finding(52%) showed negative CT findings. 3. There was dissociation between CT and SPECT findings in 7 patients in whom CT showed focal and meningeal lesions but non-focal lesion with SPECT. 4. None o positive CT finding showed negative SPECT findings. 5. SPECT never showed increased blood flow in SPECT-positive cases. 6. The SPECT scans demonstrated more lesions and wider extent of lesions than CT and more sensitive than CT in demonstrating minute blood flow changes. It is suggested that the SPECt is a useful method in evaluation of regional cerebral blood flow of head trauma patients.