A series of medicolegal autopsies on 76 patients with fatal outcome following haemorrhage from ruptured intracranial aneurysm comprised 63 surgical patients and 13 non-surgical patients (M:F 6:7 mean age 44.0 +/- 18.1 years), all of the latter with sudden fatal course or dramatically poor clinical condition on admission. The medicolegal autopsy was performed because of the sudden and unexpected nature of the death, or to exclude surgical malpractice. Postmortem angiography with vulcanising contrast medium disclosed intraventricular haemorrhage (IVH) in 12 (92%) of the non-surgical fatalities, whereas IVH was thus characterized in only 17 (27%) of the 63 fatalities who had undergone neurosurgery (P < 0.0001). The most common type of haemorrhage among surgical cases was, instead, subarachnoid haemorrhage (SAH) (P < 0.05). In 35 of the 76 cases (46%), casts of cerebral arteries demonstrated vasospasm-induced segmental narrowings, but such narrowings were no more frequent among the non-surgical cases than in surgical cases, nor did these narrowings correlate with IVH. In non-surgical patients, the haemorrhage most commonly originated from a ruptured aneurysm of the middle cerebral artery (P < 0.05), an event more frequently associated with the presence of IVH (P < 0.05) than without it. The results indicate that the main cause for sudden and unexpected death or rapidly developed poor non-operable clinical condition of patients with ruptured intracranial aneurysm is an IVH from a middle cerebral artery aneurysm, complicated in many cases by cerebral artery vasospasm.