Chorangiosis is a placental change that has not been studied, to my knowledge, by investigators who publish in English. It occurs rarely in normal pregnancies. Each year, however, more than 30,000 neonates in the United States die within the first 28 days of life. Of 1,350 singleton newborns hospitalized in a regional neonatal intensive care unit, 74 (5%) had chorangiosis. One hundred thirty-four informational items of clinical, placental, and autopsy data were evaluated with a computer program written in Microsoft Basic. Depending on the gestational age of the population studied and the severity of the chorangiosis, the incidences of neonatal death and major congenital malformations were as high as 39% and 42%, respectively. Detailed findings introduce question of etiologic association with gestational diabetes, toxemia of pregnancy, and placental infection.