The purpose of this study was to determine whether hepatocellular function is altered following hepatic ischemia and whether ATP-MgCl2 has any effect on it. To study this, total hepatic ischemia in rats was produced for 60 minutes by placing a ligature around the hepatic artery, portal vein, and the common bile duct. At the end of the ischemic period, the ligature was removed, reestablishing blood flow to the liver. The animals then received IV either 0.25 ml saline (nontreated) or 0.25 ml ATP-MgCl2 (12.5 mumoles each) (treated). Three hours following the end of ischemia, indocyanine green (ICG) clearance was determined by infusing ICG at a concentration of either 5 mg/kg body wt (low) or 25 mg/kg body wt (high). Following infusion of ICG blood samples were taken at five, six, eight, ten, 12, 15, 18, and 20 minutes thereafter to determine the ICG concentration. The clearance of ICG at low as well as at high ICG concentration was markedly depressed in the nontreated animals, suggesting that significant depression in hepatic blood flow as well as hepatocellular function was evident even three hours after ischemia. Administration of ATP-MgCl2 following hepatic ischemia, however, resulted in ICG clearance values similar to sham-operated animals when ICG was given at low as well as high concentration. Thus, ATP-MgCl2 treatment following hepatic ischemia not only seemed to restore hepatic blood flow but also active membrane transport toward normal.