 The medical diagnosis is established by finding eggs of "Opisthorchis viverrini" in feces using the Kato technique.An antigen 89 kDa of "Opisthorchis viverrini" can be detected by ELISA test.A PCR test capable of amplifying a segment of the internal transcribed spacer region of ribosomal DNA for the opisthorchiid and heterophyid flukes eggs taken directly from faeces was developed and evaluated in a rural community in central Thailand.