The authors describe eight cases of familial intracranial aneurysms occurring in four families. In the literature reviewed, familial aneurysms have different characteristics in that the incidence of the anterior communicating aneurysms is lower and that of the middle cerebral aneurysms is somewhat higher, and the age of patients at diagnosis is often younger. Although the number of patients is few, our study does not support these characteristics. A family history of intracranial aneurysms should include such high-risk factors as polycystic kidneys, coarctation of the aorta, fibromuscular dysplasia, and other connective tissue disorders.