Abstract: Postoperative changes in coagulation parameters, including the abnormal plasma prothrombin level, were studied in 95 patients who underwent liver transplantation, and the results were compared with the clinical outcome. The patients were classified into four groups: Group I had a satisfactory postoperative course, (n=76), Group II suffered graft failure or death at 31 days or more after transplantation (n=9); Group III suffered graft failure or death from 8 to 30 days after transplantation (n=4); and Group IV suffered graft failure or death within 7 days of transplantation (n=6). The Normotest, which closely reflected liver graft function, showed an increase immediately after transplantation in Group I, II, and III, but showed a marked decrease in Group IV. In patients with severe acute cellular rejection, the plasma level of abnormal prothrombin (desgamma-carboxy prothrombin) was compared with the histology of the liver biopsy specimen. When liver graft function was good after orthotopic transplantation, the Normotest value recovered to the normal range of 70% or more. Subsequently, graft function remained good when the desgamma-carboxy prothrombin level stayed low, whereas acute cellular rejection was indicated by an elevation of des-gamma-carboxy prothrombin. When the Normotest value was lower than 20% for the first 2 days after transplantation, graft failure was likely. Because des-gamma-carboxy prothrombin was not produced by graft with early failure, the des-gamma-carboxy prothrombin level also remained low. Thus, the Normotest value and the des-gamma-carboxy prothrombin level were both useful parameters for assessing hepatic function and rejection after transplantation.