Hydranencephaly is congenital disorder involving total or near-total absence of cerebrum but with intact meninges and cranial vault. CT offered a unique diagnostic tool for the evaluation of these infants but diagnosis as well as precise localization of anomaly can be-provided. We analysed US and CT findings of 5 patients with hydranencephaly who examined at Sung Ae General Hospital during last 3 years. The results were as follows: 1. 3 patients were diagnosed with aged in 11 days to 40 days. 2 patients were diagnosed in prenatal US examination with intrauterine pregnancy 40 weeks and 28 weeks. The male to female ratio was 3:1 (unknown sex in one case with intrauterine pregnancy 28 weeks) 2. Cranial vault and brain stem were intact in 5 cases. 3. Cerebellum was absent in 1 cases and intact in 4 cases. 4. Falx cerebri was intact in 2 cases partial defect in 1 cases and absent in 2 cases. 5,. Remnant cerebral hemisphere were as follows; partial and unilateral parietal lobe in 3 cases both parietal lobes in 1 cases parietal and unilateral occipital lobes in 1 cases thalamus and basal ganglia in 1cases 6, All cavities were seen in echofree cystic nature in US and low densities in CT. 7 4th ventricle was seen in 4 cases 3rd ventricle in 2cases and lateral ventricles communi-cating with echofree cystic areas. 8. Polyhydramnios and macrocephaly were seen in 2 cases in prenatal US examination.