Alcohol dehydrogenase (ADH) is an enzyme specifically located in the cytoplasm of hepatocytes. The purpose of this study was to assess the potential usefulness of serum ADH activity as a biomarker of graft function following liver transplantation. Blood samples were obtained from 26 patients who underwent living-donor liver transplantation. In patients without any post-operative complication, serum ADH activity normalized at 2.9 +/- 1.2 d. Values of serum ADH activity were remarkably elevated in patients with vascular complications, whereas they were only slightly elevated or remained within the reference range in patients with acute cellular rejections. In vascular complications, serum ADH activity peaked prior to elevation of alanine aminotransferase (ALT) and aspartate aminotransferase (AST), and once the cause of damage was resolved, the values returned to reference range more quickly than did ALT and AST. In conclusion, monitoring serum ADH activity in addition to ALT and AST may provide more sensitive ongoing graft status and valuable information for the differential diagnosis of vascular complications and acute cellular rejection.