Twenty-eight male Wistar rats were used to assess the influence of inhalation anesthetics on myocardial energy metabolism during hemorrhage. They were anesthetized with pentobarbital and divided into four groups: a control group and three others which received 1.2% halothane, 2.2% enflurane or 1.4% isoflurane, respectively. Following a 15-min stabilization period, blood was gradually withdrawn over a 5-min period from a femoral artery. Systolic blood pressure was maintained at 40 mmHg for 30 min. Immediately after hemorrhage, the heart was removed and myocardial metabolites (ATP, ADP, AMP, lactate and glycogen) were measured by the enzymatic methods. Although no significant differences could be detected in ADP, AMP and lactate among the groups, there were significant increases of ATP content in rats receiving halothane and isoflurane when compared with the controls. There were also differences in myocardial glycogen content between the control group and those receiving isoflurane with those receiving halothane or enflurane. These results suggest that halothane or isoflurane may be more desirable than enflurane for maintenance of anesthesia during hypovolemia.