Deficiency of opsonic α2surface binding (SB) glycoprotein (cold-insoluble globulin, plasma fibrinectin) is related to depressed reticuloendothelial function as well as to multiple organ failure after tissue injury and sepsis. Cryoprecipitate (250 ml), extracted from 10 units of human plasma, was infused over 60 minutes into 11 hypo-opsonemic patients with decreased renal function. Cardiac output, mean arterial pressure, creatinine clearance, and limb blood flow were measured before and at intervals of 14 to 20, 35 to 44, and 60 to 66 hours following cryoprecipitate infusion. Before infusion, the mean creatinine clearance was 30 ± 4 ml/min/M2body surface area (BSA) and increased to 40 ± 6 ml/min/M2BSA at 14 to 20 hrs (p< 0.05); to 40 ± 4 ml/min/M2BSA at 35 to 44 hrs (p< 0.05); and to 40 ± 5 ml/min/M5BSA at 60 to 66 hrs (p< 0.05). In contrast, mean arterial pressure and cardiac index at each time interval showed no significant changes from the pretreatment values of 81 ± 6 mm Hg and 3.4 ± .2 L/min/M2BSA, respectively. Limb blood flow increased significantly at 4 hours and returned to control values by 35 to 44 hours. Thus cryoprecipitate infusion to critically ill trauma and surgical patients with depressed renal function may improve glomerular filtration rate independently of mean arterial pressure or cardiac output. This improved renal function may be related to increased reticuloendothelial clearance of blood-borne particulates and/or improved microcirculatory function and lends support to the concept that RES failure may be involved in the etiology of multiple organ failure secondary to combined tissue injury and sepsis.