During the years 1950 to 1978, a total of 21 cases of Dandy-Walker syndrome were seen at the Vancouver General Hospital. Apart from hydrocephalus, the associated brain anomalies included agenesis of the corpus callosum in four cases, occipital meningocele in two and aqueductal stenosis in one patient. Systemic malformations were present in four patients and included two cases of cleft palate, one of polycystic kidneys and one of congenital rubella syndrome. The over-all mortality was 48 per cent, but has declined since 1965. Of the 12 cases treated surgically, only four have died. The number of shunt revisions was high (about two per patient). Of the 11 survivors, three have normal intelligence, four show mild mental retardation, and four are moderately to severely retarded. The differential diagnosis, clinical course and surgical therapy are discussed. It is recommended that double shunting of a lateral ventricle and of the enlarged fourth ventricle should be the primary procedure in cases associated with aqueductal stenosis or occlusion, and should be the secondary procedure in patients who exhibit recurrence of increased pressure in the posterior fossa after simple shunting of a lateral ventricle.