A prospective study was done of the results of infusion of drained blood after major procedures on the spine and hip in twenty-six patients. The Solcotrans system was used to salvage drained blood in the first six hours after the operation. Transfusion requirements, blood loss, hematocrit, temperature, prothrombin time, partial prothrombin time, platelet count, results of blood cultures, and levels of factor VIII, factor V,D-dimer, antithrombin III, plasminogen, protein C, and complement C3a des arginine were determined for some or all of the patients. A mean of 375 milliliters of blood from the Solcotrans receptacle was reinfused. All of the cultures were negative. There were no febrile reactions. The mean values for the specimens of the salvaged blood were: hematocrit, 0.20; hemoglobin, seventy-one grams per liter; plasma hemoglobin, 2.36 grams per liter; C3a des arginine, 9.4 x 10(-3) grams per liter; fat particles of less than nine micrometers in diameter, 23,643 per milliliter; and D-dimer, 205 x 10(-3) grams per liter. Studies of blood samples that were collected from patients one to two hours and twelve to eighteen hours after the transfusion showed only slight increases in fibrin split products one hour after the transfusion; these values reverted to normal by eighteen hours. No clinical coagulopathy associated with reinfusion was observed. The reinfusion of unwashed, filtered shed blood that was as much as 15 per cent of the total blood volume proved to be a safe technique after major orthopaedic procedures.