In a sibship of three brothers, two expired shortly after birth with congenital hydrocephalus, and necropsy of one revealed cerebellar agenesis and absence of the foramina of Luschka and Magendie. The non-specificity of the Dandy-Walker anomaly is discussed, and it is suggested that the present patients demonstrate another form of heritable hydrocephalus, possibly on an X-linked recessive basis.