Recognition of the disruptive vascular nature of the structural defects associated with gastroschisis and an appreciation of the embryology of the umbilical region suggest that gastroschisis results from an intrauterine interruption of the omphalomesenteric artery. This mechanism accounts for the usual location of gastroschisis to the right of the umbilical cord, the integrity of the rectus muscles in affected children, and many of the clinically observed differences between gastroschisis and omphalocele. The vascular basis of this defect explains its negligible recurrence risk and should alert the clinician to the possibility of concomitant structural defects of a similar pathogenesis.