BACKGROUND: It is commonly believed that the supine position with left uterine displacement is good for both the mother and the fetus for a cesarean section although all pregnant women do not suffer hypotension during the supine position. This study was to demonstrate whether maternal hemodynamics and infant's apgar score differences existed between the supine position with and without left uterine displacement for a cesarean section. METHODS: One hundred eighteen women for an elective repeat cesarean section were involved in this study. They were divided into 2 groups; (E) supine position (n = 65) and (C) supine position with left uterine displacement (n = 53). Hemodynamic variables (CO, CI, SVR, SVRI, SI, EF, MAP and HR) were measured at three different time points; preoperation, after intubation and 10 minutes after delivery by using a thoracic bioimpedence. The infant's apgar score was measured at 1 and 5 minutes after delivery. RESULTS: All the values of preoperation and at 10 min after delivery, were not different compared between the two groups (P > 0.05). However, after intubation, the values of HR, MBP and SVR of group C were increased significantly (P < 0.05) compared to those of group E. The infant's apgar scores (1 min, 5 min) were not different between the two groups. CONCLUSIONS: From these results, it might be thought that left uterine displacement is absolutely not necessary for an elective repeat cesarean section. However, left uterine displacement is recommended when maternal and fetal problems exist, regional anesthetic induced sympathetic blockade is done or preclampsia is diagnosed.