During a 5-year period (1978–1983) the clinical features and operative morbidity/mortality were registered prospectively for all patients in Denmark with an unruptured symptomatic (27 patients) or incidental (21 patients) intracranial saccular aneurysm. A follow-up examination was performed 2 years after diagnosis of the aneurysm. Thirty symptomatic aneurysms in 27 patients most frequently involved the visual pathways or ocular motility (66%). The median diagnostic delay for patients with impaired visual acuity was 7 months but only 14 days for patients with impaired ocular motility. The localisation of the 30 symptomatic and 23 incidental aneurysms were: internal carotid artery (73%±35%), anterior communicating artery (3%±26%) and middle cerebral artery (7%±35%). The diameters of 73% of the symptomatic aneurysms were greater than 10 mm, while the diameter of 74% of the incidental aneurysms were below 10 mm. The total operative morbidity and mortality were 15% and 4%, respectively. The mortality rate in the follow-up period was 10–11% mainly due to fatal bleeding from unoccluded aneurysms. In 21 survivors, a normal mental status was found in 43% and mild dementia was found in another 43%. The impaired visual acuity was unchanged in 67% of patients, while the ocular motility had normalised in 75%. A normal daily functional capacity was enjoyed by 57% while 43% had a moderate reduction, mostly due to visual disturbances.