Bacteriological cultures were made from pigs' tongues bought in several Belgian butchers' shops, for 3 years in succession. From 302 samples 168 Yersinia enterocolitica strains were isolated, all of serotype 3, except three strains belonging to serotype 9. The isolation rate ranged from 53 to 62.5%, depending on the year. The modified Rappaport broth supplemented with carbenicillin proved to be highly superior to the cold enrichment method for recovering the organism from this material. It is assessed that Y. enterocolitica of serotype 3 is a normal inhabitant of the oral cavity of pigs in some countries. This source of organism might play a prominent part in the epidemiology of human infections caused by these bacteria.