Objective To study the expression pattern of interleukin-13 (IL-13) in the sera and liver tissue of biliary atresia. Methods 13 infants with biliatry atresia (BA) were studied. 10 children with congenital biliary dilatation (CBD) were studied as a control. Both the BA and CBD were confirmed at operation and histological examination on the liver tissue of biopsy. The sera level of IL-13 was measured by enzyme-linked immunosorbent assay. The expression of IL-13 mRNA in liver tissue was detected with Real-time quantitative reverse transcriptase-polymerase chain reaction. The expression of IL-13 protein in liver tissue was examined by western blotting. Results The IL-13 level in sera of BA was significantly lower than that of CBD group (154.5±18.23 pg/ml vs. 268.2±19.30 pg/ml,p<0.01). Compared with CBD group, the expression of IL-13 mRNA in liver tissue was significantly lower in BA (0.0150±0.0021 vs. 0.0320±0.0050, p=0.0220), and the expression of IL-13 protein was decreased (0.3446±0.0150 vs. 0.5765±0.0215, p=0.0122). Conclusions The expression of IL-13 in the sera and liver tissue of BA is significantly elevated. It may play a key role in the pathogenesis of BA and is worthy of further investigation．