The dramatic increase in cocaine use over the past decade has led to a concern about its possible teratogenicity. We have identified 6 structural fetal anomalies which we postulate may have cocaine-induced vascular accidents as the teratogenic mechanism: 2 complex choriod plexus cysts, gastroschisis, meconium peritonitis, urethral stenosis, and radial hypoplasia. Two additional anomalous neonates were born to perinatal cocaine users. Eight of 51 (15.7%) cocaine-exposed perinates exhibited anomalies versus 120 of 2,194 (5.4%) perinates without known cocaine exposure during this time period. This represents a 3-fold relative risk (RR = 2.87, OR = 3.22, chi square = 9.68, p < 0.005) for the cocaine-exposed fetus. Subjects were all identified as cocaine users prior to ultrasound-detected anomaly and ultrasonologists were blinded to maternal drug history. The vascular disruption model as the plausible mechanism for cocaine-associated teratogenesis is supported by the type of anomalies reported. In addition, cocaine use was prospectively determined to have occurred at the critical developmental period in each case.