Background: Amnioinfusion is an intrapartum intervention with proven benefit in certain clinical situations. It is thought to be a safe treatment with few adverse effects. Cases: Two cases of fatal amniotic fluid (AF) embolism occurred in women who were treated during labor with a saline amnioinfusion. In both cases, amnioinfusion was administered after finding thick meconium staining of the AF. In addition to the amnioinfusion, common factors in these cases and three previously reported AF embolisms associated with amnioinfusion are the presence of rapid labor, meconium-stained fluid, or both. Conclusions: Amniotic fluid embolism is a rare cause of maternal morbidity and mortality. It is not known whether amnioinfusion increases the rate of its occurrence in laboring patients. No change in clinical practice is warranted on the basis of these reports; however, future reports must be examined so that any common factors can be identified. © 1994 The American College of Obstetricians and Gynecologists.