Introduction. Dandy-Walker syndrome (DWS) is a developmental abnormality characterized by dilated posterior fossa, cystic enlargement of the fourth ventricle, hypoplasia of cerebellar vermis, and its upward rotation. The affected person may suffer from psychomotor retardation, ataxia, apnea attacks, muscle weakness, occasional muscle spasm, seizures, nystagmus, and macrocephaly. However, half of the cases have average intelligence. Clinical Case. Male newborn at 36 weeks gestation obtained by cesarean section, with a history in the current pregnancy of poor prenatal control. During the fifth month of pregnancy, an ultrasound established a diagnostic suspicion of massive ventriculomegaly. At the sixth month, thinning of the cerebral cortex compression of the cerebellum in the posterior fossa was detected, and a possible ruling out of chromosomopathy related to Dandy-Walker Syndrome was suggested. Discussion. Neurologically, this disease causes multiple anomalies, such as Hemorrhagic Stroke in a Young Adult with Undiagnosed Asymptomatic Dandy–Walker Malformation (5). The embryonic development of the cerebellum and fourth ventricle causes the tentorium to be displaced upwards, and the posterior fossa enlarges. The association of hydrocephalus with DWS is due to blockage of normal cerebrospinal flow, leading to an excessive amount of fluid accumulating in and around the brain and causing an increase in intracranial pressure and head circumference, which ultimately causes neurological impairment. Conclusions. The prognosis of patients with this syndrome depends on the association with intra/extracranial malformations. Early diagnosis of central nervous system abnormalities is considered one of the first objectives of obstetric ultrasound.