To develop a test system for polymerase chain reaction (PCR) diagnosis of Opisthorchis felineus in human feces. Based on the Internet databases, the authors have developed oligonucleotide primers, as well as TaqMan tests (fluorescence label probes) specific to O. felineus genome to perform PCR with the real-time detection of a result. Conditions for PCR, including temperatures, the number of components of amplification, etc., were selected. Test systems on fecal samples from 254 subjects randomly selected and on those from 100 patients with verified opisthorchiasis, and on those from 100 healthy individuals were studies. The significance of the test systems was ascertained to be about 98%. Their sensitivity in determining O. felineus is about 10(3) copies of target DNA per ml. The efficiency of various techniques (coproovoscopy, enzyme immunoassay, PCR) was compared to detect Opisthorchis invasion.