We reviewed records from 251 consecutive cesarean deliveries performed over a six-month period to evaluate the effect of amnioinfusion during labor on the incidence of postpartum endometritis in patients who delivered by cesarean section. One hundred fifty-four patients were excluded because they were not in labor, were at less than 35 weeks' gestation or received antibiotics during labor. Twenty-three of the remaining 97 patients received amnioinfusion during labor and represented the study group. Seventy-four patients did not receive amnioinfusion during labor and were used as controls. The incidence of postpartum endometritis in the amnioinfusion group was 13%, while the incidence in the group not receiving amnioinfusion was 38% (relative risk, 0.34; 95% confidence interval, 0.13-0.88; P = .026). Amnioinfusion during labor appears to significantly decrease the incidence of postpartum endometritis in patients subsequently undergoing cesarean delivery.