Between 1975 and 1989, 58 patients, 32 females and 26 males, mean age 50 years, with intracranial giant aneurysms with a diameter more than 2.5 cm were treated at our clinic. 48% of the patients presented with subarachnoidal hemorrhage. The most of the other 30 patients presented with cranial nerve dysfunctions. The most common site of the aneurysm was the internal carotid artery (25 cases, 43%), followed by the anterior cerebral artery (14%), and the vertebro-basilar region (11 cases, 19%). In 14 patients direct surgery was not performed because of the poor general condition of the patient, the high risks, or non-consent. In seven patients (12%) the aneurysm had been misdiagnosed as meningeoma, pituitary-adenoma, craniopharyngeoma or glioblastoma. 47% of all patients were discharged as "independent" and 19% died. Patients without SAH had better chance of survival: 7% of patients without SAH died and 29% of patients with hemorrhage. 50% of patients without hemorrhage were discharged as "independent" but only 18% of patients with SAH. Because of the high incidence of hemorrhage and the better prognosis for patients without hemorrhage, we recommend routine surgical treatment of patients with giant aneurysms.