Intracranial saccular aneurysms in childhood are rare neurosurgical lesions, occurring in 1–3% of large epidemiological aneurysm series. Analysis of previous reports indicates several distinct characteristics of this entity. First, there is a predominant male:female ratio approaching 2:1. Second, a disproportionately high number of these aneurysms arise at peripheral locations on the arterial tree. Third, approximately half of them are large or even giant aneurysms. These identifiable characteristics suggest that aneurysms in the younger age group may be a distinct pathophysiological entity from aneurysm in the adult population. In adults, epidemiological evidence indicates that‘acquired’factors such as hypertension, cigarette smoking, alcohol consumption, and oral contraceptive use together with‘intrinsic’or‘vascular’factors are causally related to the formation and rupture of cerebral aneurysms. Inherently, some of the‘acquired’factors must be of minor importance in aneurysm formation and rupture in childhood, whereas the‘intrinsic’factors may have a greater importance.