Biliary atresia (BA) is the leading indication for liver transplantation (LTx) during childhood. Predictive markers for progression are lacking. We investigated the correlation between quantified fibrosis of the liver at the time of Kasai hepatic portoenterostomy (KPE) and the clinical course. Liver tissue was obtained at the time of KPE in 53 children and stained with Picrosirius red. The mean volume of fibrosis per number of periportal fields (Vfib) and the Ishak score were calculated. Vfib was 3.9%. Transplant-free survival was significantly higher in those patients with Vfib < 2.5% (P < 0.05, Kaplan-Meier analysis). Vfib < 2.5% predicted transplant-free survival with a sensitivity of 100% and a specificity of 48% (positive predictive value: 100%, negative predictive value: 17%). Vfib was correlated with bilirubin 6 months after KPE (Bili6m). The negative predictive value could be enhanced to 23% if Vfib < 2.5% was combined with Bili6m < 20 micromol/L. The Ishak score showed no correlation with transplant-free survival or Vfib. Detection of Vfib at the time of KPE is a valid marker in predicting transplant-free survival in children with BA. This method should be considered an integral part of scoring systems predicting the indication for LTx. Liver Transpl 15:876-882, 2009. (c) 2009 AASLD.