Cerebral blood flow and cerebrospinal fluid amino acids were investigated in patients with leukoaraiosis on magnetic resonance imaging. Ten patients with leukoaraiosis and without significant cerebral infarction and ten age-matched controls without abnormality on magnetic resonance imaging were studied. The regional cerebral blood flow was measured using the stable xenon computed tomography method. The blood flow was significantly lower in the leukoaraiosis area in the leukoaraiosis group than in the same area in the control group. The cerebrospinal fluid glutamate concentration was significantly higher in the leukoaraiosis group than in the control group. There was a significant negative correlation between the blood flow in the leukoaraiosis area and the cerebrospinal fluid glutamate concentration. The high concentration of cerebrospinal fluid glutamate in patients with leukoaraiosis is considered to be related to ischaemia.