It has recently been reported that the use of halogenated agents during balanced general anesthesia may result in an increase in blood loss associated with cesarean section. This report has been criticized for failure to control for a variety of other factors that may have contributed to the increased blood loss, particularly the indication for and type of cesarean section. The present study was designed in an attempt to resolve this criticism. Blood loss was evaluated in uncomplicated patients undergoing elective repeat cesarean section under either general anesthesia using a halogenated agent (isoflurane) or regional anesthesia (spinal/epidural). All 117 singleton term, nonlaboring women underwent repeat low transverse cesarean section performed through a midline abdominal incision. Exclusion criteria included maternal medical complications, abnormal placentation, polyhydramnios, presence of uterine leiomyomas, and intraoperative complications. Seventy-five patients (64%) received regional and 42 (36%) received general anesthesia. A greater proportion of women undergoing general anesthesia experienced a postoperative decrease in hematocritof 5 vol% or more compared with patients receiving regional anesthesia (10 of 42 versus 5 of 75, p = 0.018). Thus, we conclude that women undergoing uncomplicated elective repeat cesarean section under general anesthesia supplemented with a halogenated agent are at risk for increased blood loss compared with those women receiving regional anesthesia. However, the increased blood loss was not clinically significant in this study, since none of the patients required transfusion. © 1992, by Thieme Medical Publishers, Inc. All rights reserved.