Therefore in this study, we identified and characterized C. sinensis MRP4 (CsMRP4), the first MRP4 in trematodes, at the in silico, molecular, and biochemical levels. The structure of CsMRP4 was built using homology modeling, and the structural features and bile acid-binding affinities were investigated. CsMRP4 was found to be localized mainly in the mesenchymal tissues and oral suckers of C. sinensis adults and metacercariae.