The purpose of this investigation was to study the indication of cerebral angiography in recent operations for cerebral aneurysms. Cerebral angiography has been used for diagnoses and operations for cerebral aneurysms, but, as the diagnostic procedures such as magnetic resonance angiography (MRA) and three dimensional computed tomographic angiography (3D-CTA) have made remarkable progress, cerebral angiography is not always an indispensable diagnostic tool for cerebral aneurysm operations. One hundred nineteen patients (including 40 patients with ruptured aneurysms) out of 165 patients (including 61 patients with ruptured aneurysms) were diagnosed and operated on following MRA and 3D-CTA. All of these cases of cerebral aneurysms were operated uneventfully without the need for cerebral angiography. We concluded that cerebral angiography is not needed for diagnoses and operations of small common cerebral aneurysms such as middle cerebral artery aneurysms, internal carotid artery-posterior communicating artery aneurysms and anterior communicating artery aneurysms. Cerebral angiography is necessary only in relatively large aneurysms to confirm the dynamic circulation of the cerebral blood flow before operation.