A 3-month-old female infant with Dandy-Walker malformation manifesting as hydrocephalus was treated successfully by only ventriculoperitoneal shunting. A flexible neuroendoscope was used intraoperatively to confirm the patency of the aqueduct, i.e. communication of the ventricular system and the cyst in the posterior fossa. Direct confirmation of the patency of the aqueduct and cyst communication is valuable to select the shunt procedure in the treatment of Dandy-Walker malformation.