The pathophysiology of Möbius syndrome has been debated for decades. A vascular etiology is currently favored because it explains the wide clinical spectrum of this syndrome. An infant is reported who was born with Möbius syndrome after a pregnancy complicated by heavy maternal use of cocaine and alcohol. We speculate that cocaine-induced vasoconstriction at a critical time of cerebrovascular development produced a vascular disruption sequence leading to the Möbius syndrome. © 1993.