Purpose: The correlation between the histological findings of the intrahepatic biliary epithelium and postoperative bile drainage in biliary atresia (BA) was investigated. Methods: The patients with BA were classified into 2 groups, consisting of a good bile drainage group (GBD, n = 14, mean age at initial operation, 57.6 ± 18.0 days) and a poor bile drainage group (PBD, n = 11, mean age at initial operation, 86.9 ± 42.7 days). Liver specimens from an initial Kasai's operation were examined by immunostaining using anticytokeratin 7 (CK7) antibody and anti-MIB-1 antibody. The number of CK7-positive cells in the bile ductules was microscopically calculated within the 40-μm-thick interstitium along the limiting plate (LP), and the CK7-positive cell number per unit length of the LP was estimated. In addition, the MIB-1 index in bile ductules also was determined. Results: The number of CK7-positive cells in PBD was significantly higher than that in GBD (167.6 ± 45.6 v 117.8 ± 32.4/mm, P < .05). However, the MIB-1 index in biliary cells did not differ between the 2 groups. Conclusion: An increased number of intrahepatic bile duct epithelial cells in liver specimens at the initial operation may be a poor prognostic factor in BA and appears to depend on the duration of bile stasis rather than the degree of bile stasis.