Background/Purpose: The purpose of this study was to determine reliable predictors of outcome of biliary atresia (BA) after Kasai's operation. Patients and Methods: Fifty-four BA cases that underwent Kasai's operation at our institution over two decades were reviewed. The cases were divided into two groups: Group I: cases that required liver transplantation or died (n = 30) and Group II: cases alive with the native liver. Serum levels of total bilirubin (TB), direct bilirubin (DB), aspartate aminotransferase (AST), alanine aminotransferase (ALT), and gamma-glutamyltransferase (GGT) were measured sequentially after surgery. For cut-off determination, receiver operating characteristic (ROC) analysis was employed. Results: Serum TB, DB, AST, and ALT in Group I were significantly higher than those in Group II at 1, 2, and 3 months after surgery (p < .05). The most reliable cut-offs determined by ROC analysis were DB of 0.7 mg/dl at 2 months (sensitivity; 93%, specificity; 75%) and AST of 94 IU/L at 2 months (sensitivity; 87%, specificity; 71%). The 54 cases were re-divided into three groups according to the cut-off values: group G (good) with DB and AST < cut-offs (n = 16; Group I:II = 1: 15), group M (moderate) with DB or AST >= cut-offs (n = 9; Group I:II = 4: 5), and group P (poor) with DB and AST = cut-offs (n = 29; Group I: II = 25: 4). The 15-year survival rate in groups G, M, and P was 94%, 44%, and 22%, respectively (p < .001). Conclusion: The combination of serum DB and AST at 2 months after Kasai's operation is a reliable predictor of long-term BA outcome. (c) 2013 Elsevier Inc. All rights reserved.