Idiopathic HES is characterlized by prolonged eosinophilia without an identifiable underlying cause and multiple-organ dysfunction. We report a case of a LDLT for a 12-yr-old Japanese girl with BA accompanied by HES. Histological examination of the resected liver showed biliary cirrhosis with dense eosinophilic infiltration of portal tracts and the lobules of the liver. She developed portal vein thrombosis on post-operative day 10 and the histopathological findings of the thrombus revealed dense eosinophilic deposition, suggesting that HES might have influenced the formation of this thrombus. Liver graft biopsies also demonstrated the presence of activated eosinophilils with biliary damage. Blood chemistry findings suggested liver dysfunction as a result of the eosinophilic infiltrations. Prednisolone treatment improved the liver dysfunction. Four years after LDLT, she remains clinically well on prednisolone at 0.3 mg/kg/day, with an eosinophil count ranging from 10 to 15%. A literature review has not shown any previous reports of HES with BA. This case demonstrates the possibility of an association between eosinophilic infiltration and liver dysfunction during follow-up for BA and after LDLT.