• A young man with polycystic kidney disease was seen initially with a brainstem infarction. Postmortem examination disclosed a dissecting aneurysm of the basilar artery and a saccular aneurysm of the right vertebral artery. Dissecting intracranial aneurysms rarely are associated with saccular aneurysms and, to our knowledge, have not been reported in association with polycystic kidney disease.