In an attempt to investigate the effect of intracerebral hematoma on cortical blood flow and perifocal ischemia, an experimental rat model of intracerebral hematoma was used. In a total of 44 adult male rats, cortical blood flow was studied using on H2 clearance method. The ischemic zone was investigated under light microscopy. In order to potentiate the effect of intracerebral hematoma, bilateral ligation of the common carotid artery was simultaneously performed in twelve rats. Intracerebral hematoma was induced by injecting 30nl of autologous arterial blood. Ipsilateral cortical blood flow decreased to 67.4% of baseline after the formation of intracerebral hematoma in the basal ganglia ; bilateral ligation of the common carotid artery alone decreased cortical blood flow to 59.4% of baseline ; and intracerebral hematoma formation after ligation decreased the flow to 20.5% of baseline. Neurological grades were worst in the last mentioned group, and in no group was perifocal infarction detected by light microscopy. These data suggest that the occurrence of intracerebral hematoma markedly decreases the cortical blood flow. Additionally, in a situation of compromised cerebral blood flow, the development of intracerebral hematoma can lead to a further decrease in flow, resulting in a worse neurological outcome, despite the absence of detectable histological difference.