OBJECTIVE: To delve into the clinical and CT imaging manifestations of hydranencephaly, a rare congenital post-neurulation disorder occurring during the second trimester, characterized by the destruction of cerebral hemispheres and cranial cavity filled with cerebrospinal fluid (CSF). This research aims to enhance our understanding of hydranencephaly and establish a standard for its imaging diagnosis. METHODS: A retrospective analysis was conducted using the brain CT images and clinical data of 26 pediatric patients diagnosed with hydranencephaly. RESULTS: At birth, the primitive reflexes were generally preserved in these infants, who exhibited a spectrum of symptoms including progressive enlargement of head circumference, epilepsy, cerebral palsy, intellectual disability, developmental delay, lethargy, convulsive spasms, and varying degrees of visual and auditory impairment. These infants may also present with other congenital malformations or abnormalities. The primary CT imaging findings revealed complete or near-complete absence of bilateral cerebral hemispheres, replaced by CSF. Specifically, there were 5 cases of complete absence of cerebral hemispheres, with minimal residual brain tissue observed in 17 cases. Bilateral ventricles were approximately normal in 3 cases and completely absent in 19 cases. Falx cerebri was incomplete or/and displaced in 12 cases, and 3 cases were concurrent with Dandy-Walker syndrome. CONCLUSION: Hydranencephaly is a congenital disease characterized by destruction of the cerebral hemispheres. CT scan can provide accurate and reliable imaging evidence for the diagnosis of hydranencephaly.