AIM: To describe the diagnostic criteria for acute liver failure due to Wilson disease (WD), which is an uncommon cause of acute liver failure (ALF). METHODS: We compared findings of patients presenting with ALF due to WD to those with ALF of other etiologies. RESULTS: Previously described criteria, such as low alkaline phosphatase activity, ratio of low alkaline phosphatase to total bilirubin or ratio of high aspartate aminotransferase (AST) to alanine aminotransferase (ALT), failed to identify patients with ALF due to WD. There were significant differences in low ALT and AST activities (53 ± 43 vs 1982 ± 938, P < 0.0001 and 87 ± 44 vs 2756 ± 2941, P = 0.037, respectively), low choline esterase activity (1.79 ± 1.2 vs 4.30 ± 1.2, P = 0.009), high urine copper concentrations (93.4 ± 144.0 vs 3.5 ± 1.8, P = 0.001) and low hemoglobin (7.0 ± 2.2 vs 12.6 ± 1.8, P < 0.0001) in patients with ALF caused by WD as compared with other etiologies. Interestingly, 4 of 7 patients with ALF due to WD survived without liver transplantation. CONCLUSION: In ALF, these criteria can help establish a diagnosis of WD. Where applicable, slit- lamp examination for presence of Kayser-Fleischer rings and liver biopsy for determination of hepatic copper concentration still remain important for the diagnosis of ALF due to WD. The need for liver transplantation should be evaluated carefully as the prognosis is not necessarily fatal. AIM: To describe the diagnostic criteria for acute liver failure due to Wilson disease (WD), which is an uncommon cause of acute liver failure (ALF). METHODS: We compared findings of patients presenting with ALF due to WD to those with ALF of other etiologies. RESULTS: Previously described criteria, such as low alkaline phosphatase activity, ratio of low alkaline phosphatase to total bilirubin or ratio of high aspartate aminotransferase (AST) to alanine aminotransferase (ALT), failed to identify patients with ALF due to WD. There were significant differences in low ALT and AST activities (53 ± 43 vs. 1982 ± 938, P <0.0001 and 87 ± 44 vs 2756 ± 2941, P = 0.037, respectively), low choline esterase activity (1.79 ± 1.2 vs. 4.30 ± 1.2 , P = 0.009), high urine copper concentrations (93.4 ± 144.0 vs 3.5 ± 1.8, P = 0.001) and low hemoglobin (7.0 ± 2.2 vs 12.6 ± 1.8, P <0.0001) in patients with ALF caused by WD as compared with other etiologies. Interestingly, 4 of 7 patients with ALF due to WD survived without liver transplantation. CONCLUSION: In ALF, these criteria can help establish a diagnosis of WD. Where applicable, slit-lamp examination for presence of Kayser-Fleischer rings and liver biopsy for determination of hepatic copper concentration still remain important for the diagnosis of ALF due to WD. The need for liver transplantation should be carefully chosen as the prognosis is not necessarily fatal.