Two brothers had a congenital cerebral malformation suggestive of a destructive process of the parenchyma; the first was hydranencephalic with extensive heterotopias. The second had focal microgyria and subcortical heterotopias. The precise origin of this disorder, which occurred two times in the same sibship, was not found; there is no reported genetic disease capable to cause such destructive brain lesion. The possibility of a persistent infectious disorder causing repetitive disturbance of gestation is discussed; it has not been proved. A fortuitous association cannot be excluded.