Albumin, when added to a standard resuscitation regimen, is purported to enhance plasma volume, improve pulmonary function by its oncotic effect, and prevent renal failure by augmenting salt and water excreation. These factors were evaluated in a prospective randomized manner in 52 injured patients who received an average of 15.3 transfusions, 9.6 L balanced electrolyte solution, and 9.8 L fresh frozen plasma prior to and during operation; 27 patients received an average of 25 gm albumin (Alb) during operation and 150 gm/day for 3 to days thereafter.Alb caused a significant (p= < 0.05) increase in total protein and serum Alb levels. Plasma volume averaged 3,987 ml in Alb patients and 3,693 ml in non-Alb patients. Despite this urine output and sodium clearance were less, averaging 2.5 and 1.1 ml/min compared to 3.6 and 2.6 ml/min in non-Alb patients. Alb patients also had greater dependency on ventilatory support, averaging 8 days compared to 3 days in non-Alb patients. Central venous and pulmonary wedge pressures were higher in Alb patients.Alb, when added to a standard resuscitation regimen for hypovolemic shock, increases plasma volume both by its oncotic effects and by its interference with saline diuresis. Its subsequent effects on cardiopulmonary function appear to be detrimental and are under investigation.