1. Objectives This study was carried out to investigate the equilibrium functional difference according to mean velocity of basilar artery with Sasang Constitution. 2. Methods We analyzed the data of 300 adults(194 males, 106 females), who visited oriental hospital of D university for medical examiation, which includes Sasang constitution examination, equilibrium function test, transcranial doppler ultrasonography(TCD). We evaluated the trace length and envelop area of open eyes and closed eyes, mean velocity of basilar artery and analyzed its statistical data. 3. Results and Conclusions 1) Within all subjects, trace length and envelop area of closed eyes were significantly lower, in the order of increased mean velocity of basilar artery group, normal mean velocity of basilar artery group and decreased mean velocity of basilar artery group. 2) No significantly difference was seen between the mean velocity of basilar artery and equilibrium function in Soyangin and Soeumin. 3) When closed eyes, trace length were significantly lower in order of increased mean velocity of basilar artery group, normal mean velocity of basilar artery group and decreased mean velocity of basilar artery group, in Taeeumin.