A primipara with an uncomplicated pregnancy was induced for labor. As uterine contractions commenced, an antepartum bleeding occurred, followed by fetal distress. An anemic fetus was delivered by cesarean section. The placenta was annular in shape with velamentous blood vessels, one of which was ruptured and sealed off by a fresh thrombus. A zonary or ring-shaped placenta is extremely rare: to our knowledge, this is the first case to be published.