This study was conducted to investigate changes of blood metabolites and enzyme activities at different slaughter ages of Hanwoo cattle. Blood samples were taken from six hundred thirty two steers (24~33 months of age) and one hundred twenty eight bulls (17~24 months of age) by venipuncture from caudal vein immediately prior to slaughter. Glucose concentrations were linearly increased (P<0.001) with increases of the slaughter age in steers, and blood urea nitrogen (BUN) concentrations were linearly decreased (P<0.001) with increases of the slaughter age in steers. Likewise, glucose and albumin concentrations in bulls were linearly decreased (P=0.009 and P<0.001, respectively) with increases of the slaughter age. BUN, cholesterol, triglycerides, and total cholesterol concentrations were linearly increased (P<0.001, 0.018 and 0.002, respectively), and creatinine concentrations were quadratically increased (P=0.009) with increases of the slaughter age. Activity of gamma glutamyltransferase (${gamma}$-GT) and aspartate aminotransferase (AST) was linearly increased (P<0.001) with increases of the slaughter age in both steers and bulls, whereas alanine aminotransferase (ALT) was not affected by increasing slaughter age. In addition, the concentrations of ${gamma}$-GT and AST were higher (P<0.05) for bulls than those of steers at 24 months of age. Increased levels of ${gamma}$-GT and AST indicate impaired liver function; it may be associated with increases of concentrate level which is a concomitant of the extended fattening periods in Hanwoo feeding. In conclusion, the results in the present study may be one of the useful information for diagnosis of the metabolic disorder in Hanwoo cattle.