From 43 (35.8%) out of 120 samples of pasteurized milk used by volunteers 182 cultures of five Yersinia species--Y. enterocolitica, biovar 1 (70.3%), Y. intermedia (18.1%), Y. frederiksenii (7.7%), Y. kristensenii (3.3%) and Y. aldovae (0.5%)--were isolated in the course of bacteriological studies carried out in 1987-1990. The isolated Yersinia cultures belonged to nonpathogenic pyraminidaze-positive serovars. Yersinia pathogenic bio/serovars (4/O3, 2/O9, 1B/O8) were not detected. No deviations from the normal state were registered in the volunteers drinking pasteurized milk, and Yersinia could be isolated from their feces only during the first 3 days following milk consumption. In 390 patients examined for the presence of Yersinia infections the isolation rate of Yersinia of biovar 1 (99.6% of the cultures) varied between 4.4% and 21.3% and correlated with the increase of the isolation rate from milk (13.6% to 53.9%). The results of the study suggest that unboiled pasteurized milk contributes to the spread of Yersinia carriership among the population.