The aim of the investigations was the identification of pathogenic markers of Yersinia enterocolitica isolated from humans and pigs by means of polimerase chain reaction (PCR). Two pairs of the starters Ail-a, Ail-b and Yst-a, Yst-b were used. One hundred twenty-two strains of Yersinia enterocolitica were tested. Among them, 0:3, 0:9, 0:2, 0:5 serogroups were identified. A multiplex polymerase chain reaction (PCR) was developed to detect the presence of the chromosomal ail and gist genes of the Yersinia enterocolitica strains tested. The results of the multiplex PCR for Y. enterocolitica strains indicated that all human and animal isolates examined, belonging to four serobiotypes, gave a positive reaction for the ail gene and yst gene, yielding fragments of 356 and 134 base pairs respectively. PCR products were not obtained with any of the two primers while using template DNA from Y. pseudotuberculosis, Y. kristensenii, Salmonella enteritidis, Shigella flexnerii and Citrobacter freundii. The presence of the chromosomal ail and yst genes in the Yersinia enterocolitica strains from humans and pigs indicates that pigs are a significant reservoir of pathogenic rod Y. enterocolitica.