Hemorrhagic shock was produced in conscious rats by bleeding the animals to a mean arterial pressure of 40 mm Hg that was maintained for 1½ hours. At the end of the shock period, the animals received (1) blood alone; or (2) blood plus Ringer lactate; or (3) adenosine triphosphate-magnesium chloride (ATP-MgCl2) followed by blood; or (4) adenosine diphosphate-MgCl2(ADP-MgCl2), or adenosine phosphate-MgCl2(AP-MgCl2), or adenosine-MgCl2followed by blood and were killed three minutes afterward. Analysis of liver and kidney showed that ATP levels decreased during shock, and they remained low when blood, blood plus Ringer lactate or ADP-MgCl2, AP-MgCl2, or adenosine-MgCl2were given. Adenosine triphosphate levels returned to normal in both tissues only when ATP-MgCl2and blood were given. The effect of ATP-MgCl2in restoring ATP levels of liver and kidney may be through provision of the high-energy phosphate compound. © 1974, American Medical Association. All rights reserved.