The WD40-repeat proteins serve as a platform coordinating partner proteins and are involved in a range of regulatory cellular functions. A WD40-repeat protein (CsWD1) of Clonorchis sinensis previously cloned is expressed stage-specifically in the tegumental syncytium of C. sinensis metacercariae. In the present study, interact-ing proteins with the CsWD1 protein was purified by immunoprecipitation and 2 dimension gel electrophoresis from the C. sinensis metacercaria soluble extract, and tryptic peptides were analyzed by LC/ESI-MS. Putative partner proteins were annotated to be actin-2, glyceraldehyde-3-phosphate dehydrogenase, and hypothetical and unmanned proteins. The CsWD1 protein was predicted to contain 3 conserved actin-interacting residues on its functional surface. With these results, the CsWD1 protein is suggested to be an actin-interacting protein of C. sinensis.