Hemorrhagic endovasculitis of the placenta has been reported to correlate with intrauterine growth retardation, perinatal morbidity and mortality, and long-term developmental delay. At a regional obstetric hospital we identified 13 cases of hemorrhagic endovasculitis among 1938 placentas from singleton pregnancies of greater than or equal to 20 weeks' gestation over a 3-month period, an incidence of 0.67% of unselected pregnancies. All cases were live-births without intrauterine growth retardation. Associated clinical features were pregnancy-induced hypertension, nuchal cord at delivery, and postterm gestation. One infant had severe perinatal asphyxia with long-term psychomotor retardation. In the placenta, hemorrhagic endovasculitis was associated with infarction, fetal vessel thrombosis, and villitis of unknown cause. Interference with umbilical blood flow or regional compromise of villous perfusion may be an initiating event in the development of this lesion.