A prospective study was performed to investigate whether carotid endarterectomy was accompanied by changes in the cerebral circulation and gait of patients with gait disturbance caused by cerebral ischemia from an internal carotid artery flow lesion. Gait analysis was performed pre-and postoperatively in 16 patients who had a gait disturbance from April 1997 to May 1998. A correlation between change of volume flow measured by duplex sonography, a change in cerebral perfusion (CP) by single photon emission computed tomography (SPECT), the status of collateral circulation by cerebral angiogram or magnetic resonance angiogram, and improvement of gait disturbance was analyzed. Of 16 patients with gait disturbance, 14 (87.5%) showed improvement in various gait analysis parameters. Statistical significance was noted in cadence, speed, stride length, step time, and knee range of motion (P<05). Dramatic gait improvement was observed in 8 patients who had markedly increased Doppler volume flow after carotid endarterectomy. Among those 8 patients, 7 had a significant increase of CP as measured by SPECT and an incomplete circle of Willis. In conclusion, the most significant gait improvement was noted in patients who had severely decreased preoperative volume flow, an incomplete circle of Willis, and significantly increased postoperative CP as measured by SPECT.