OBJECTIVE: This study aimed to investigate the value of the liver function test in the differential diagnosis of infantile hepatitis syndrome (IHS) and biliary atresia (BA) by analyzing seven conventional serological markers in this test using receiver operating characteristic (ROC) curves. METHODS: Serum levels of seven conventional serological markers: alanine aminotransferase (ALT), aspartate aminotransferase (AST), γ-glutamyl transpeptidase (γ-GT), alkaline phosphatase (ALP), total bilirubin (TB), conjugated bilirubin (CB) and serum albumin (ALB) were measured in 103 children with IHS and 60 children with BA. ROC curves were used to evaluate the sensitivity, specificity, positive and predictive values and optimal cut-off. The united tests (parallel test and serial test) of γ-GT, TB and CB were performed to elevate diagnostic efficiency. RESULTS: Compared with the IHS group, the BA group had significantly increased serum ALT, AST, γ-GT, TB and CB levels (P<0.01). The area under ROC (AUCROC) of AST, γ-GT, CB and TB was 0.77, 0.881, 0.841 and 0.87, respectively. γ-GT showed the highest AUCROC, specificity, positive predictive value and positive likelihood ratio in the diagnosis of BA, followed by CB, TB and AST in turn. The negative predictive value of CB was the highest, followed by TB. The negative likelihood ratio of CB was the lowest but its Youden index was the highest. The Youden index of γ-GT and TB was lower than that of CB. After the parallel tests, the sensitivity and negative predictive value of γ-GT, CB and TB increased to 100%. After the serial tests, the specificity of γ-GT, CB and TB increased to 90.4% and the positive predictive value increased to 87.5%. CONCLUSIONS: The measurement of γ-GT, TB and CB levels are valuable in the differential diagnosis of BA and IHS. An imaging examination is required in the parallel test positive patients.［Chin J Contemp Pediatr, 2009, 11 (12):953-956］