There are several methods for measurement of cerebral blood flow. A method using Tc-99m DTPA which was injected via antecubital vein and monitored extracranially with gamma camera is described here. In this method, the brain scan and CBF mesurement were performed with scan and CBF were usually studied separately. The results were as follow: 1) Total candidates were 53, male 34 and female 19, who have no evidence of neurologic, cardiac or kidney problems. 2) By this method, the normal CBF of Korean was 54.12±6.49ml/min/100g of brain tissue. 3) The CBF of male was 54.06±5.9ml/min/100g of brain tissue, female was 54.89±6.51ml/min/100g, so there was no definite sex difference. 4) The CBF under 10 years of age was 54.12±2.5ml/min/100g, 11-20 years of age was 52.33±6.lml/min/100g, 21∼60 years of age was 52.86±5.06ml/min/100g, and over 61 years of age was 55.43±4.84ml/min/100g, so there was no significant difference of CBF by age.