Subarachnoid hemorrhage (SAH) secondary to ruptured saccular intracranial aneurysm (IA) is a complex trait, with both genetic and environmental risk factors playing an important part. The 30-day mortality rate of patients with SAH is 40% to 44%, with many survivors suffering from major disability. Because most of the mortality after SAH is caused by rapid and massive brain injury from the initial bleeding, primary prevention of aneurysm formation and rupture is of paramount importance. This article reviews the evidence supporting a genetic predisposition to SAH from saccular IA, the conditions commonly associated with saccular IA, and the search for genetic risk factors.