The authors report the case of a 57-year-old, right-handed female who experienced a sudden acute headache, followed by a period of confusion and fever. Over the next week she developed language disturbances. No diagnosis was established. Three weeks later she was referred to the neurologist, complaining of a right frontal headache. The C.T. scans with and without contrast enhancement were suggestive of an aneurysm in each sylvian fissure. The angiography disclosed the presence of four aneurysms: a large left M.C.A. aneurysm, a larger right M.C.A. aneurysm, an aneurysm on the anterior communicating aneurysm and a small right M.C.A. aneurysm located more distally. The left M.C.A. aneurysm was presumably ruptured and responsible for the initial symptoms. The right M.C.A. aneurysms was apparently unruptured, but accounted for the persistent right headache. The other two aneurysms were thought to be asymptomatic. The left M.C.A. was operated first. Blood in the sylvian fissure confirmed the earlier rupture. Two weeks later, the three other aneurysms were surgically treated, via the same right pterional approach. No sign of hemorrhage was found on the right side. The post-operative angiogram demonstrated the disappearance of all four aneurysms. Three months later, the patient was able to resume her previous occupations and clinically, she demonstrated no sign of psychological or intellectual disturbances. The management of multiple and bilateral cerebral aneurysms is discussed, as well as the management of asymptomatic aneurysms.