This case report describes a finding of vascular malformation of an aborted foetus of gestational age of the 22nd week. This concerns meningocerebral angiodysplasia, located in the posterior fossa and around the thalami. This disease is rare and is often accompanied by renal agenesis. The finding was complicated by hydrocephalus. Our report compares all three diagnostic methods (prenatal ultrasonography, post-mortem MR and autopsy). Prenatal ultrasonography described only hydrocephalus and reduction of cerebral parenchyma. MR displayed the extent of the malformation, the exact diagnosis was however determined by histological examination. MR described agenesis of structures of midbrain, which was confirmed by autopsy.