Activity of plasma proteolytic systems was studied in outbred albino rats with acute renal failure. The possibility of treating this disorder with acute phase protein alpha-1-acid glycoprotein was evaluated. Acute renal failure was induced by single subcutaneous injection of mercury chloride (II). The parameters were evaluated on day 5 postinjection. alpha-1-Acid glycoprotein in a dose of 150 mg/kg was administered 3 times. Acute renal failure was accompanied by activation of the complement system and fibrin formation (with factors for the intrinsic and common pathways of blood coagulation) and inhibition of the fibrinolytic system and antithrombin activity. Treatment with glycoprotein was followed by partial recovery of fibrin formation and complement system. These changes were probably related to accumulation of glycoprotein in the renal tissue and in situ protective effect.