A recombinant pore-forming peptide of Clonorchis sinensis, clonorin, was evaluated for serodiagnostic reagent of clonorchiasis by enzyme-linked immunosorbent assay detecting IgG antibody. Recombinant clonorin showed 100% specificity and low sensitivity for sera of human clonorchiasis. In contrast, C. sinensis crude antigen revealed lower specificity and higher sensitivity than recombinant clonorin did. In sera of experimental rabbits, clonorin-specific IgG antibody was increased remarkably 8 weeks after the infection and retained around level of OD(490)=0.2 for 1 year. With excellent antigenic specificity, it is suggested that the recombinant clonorin can be used as an ingredient of the cocktail antigen for serodiagnosis of clonorchiasis from early stages of the infection.