The effects of supplemental albumin infusion on serum protein homeostasis were studied in 94 seriously injured patients who received an average of 14.4 transfusion, 9.2 L electrolyte solution, and 829 ml fresh frozen plasma before and during operation. Based on randomization, 46 patients received an average of 31 gm albumin during operation followed by 150 gm/day for 5 days; 48 patients received no albumin. Supplemental albumin caused a significant (p = less than 0.05) increase in total serum protein and albumin concentrations. In contrast, supplemental albumin caused a significant decrease in alpha 1 globulin, alpha 2 globulin, beta globulin, gamma globulin, and fibrinogen levels. The prothrombin time used as index of prothrombin concentration was significantly prolonged in albumin patients. These changes, not previously documented, need further evaluation to determine clinical significance.