40, 1-14-year-old children suffering from congenital hemiparesis were re-examined neurologically and admitted to CT. According to our morphological results we found three different types of CT patterns: 1. unilateral enlargement of the lateral ventricle or parts of it (20 patients), 2. cavity in the cortex and subcortical white matter within the supply area of the middle cerebral artery (17 patients), 3. normal CT scans (3 patients). Patients with a cortical and subcortical cavity consistently had a moderate to severe hemiparesis and suffered more often from epilepsy and intellectual impairment than patients with unilateral ventricular enlargement and those with normal CT findings. Most patients with cortical defects had a history of perinatal complications, while abnormal pregnancies and prematurity prevailed in patients with unilateral ventricular enlargement. We believe that a cavity in the cortex and subcortical white matter is of arterial-ischemic origin, whereas unilateral ventricular enlargement with destruction of the deep white matter is related to venous hemorrhage. But it must be emphasized that CT cannot detect the causes, mechanisms and timing of the underlying brain lesions in congenital hemiparesis.