To diagnose intestinal yersiniosis, the detection of antigen-binding lymphocytes (ABL) with respect to Y. enterocolitica O3, O5 and O9 is proposed. Experiments on the immunization of rabbits with Y. enterocolitica LPS of these serovars revealed that immunoreagents, according to the data of cross antigen-dependent rosette formation and its inhibition, had species specificity (ABL of rabbits immunized with Y. enterocolitica did not interact with Salmonella, Shigella and Y. pseudotuberculosis antigens) and serovar specificity. Cross reactions in the detection of ABL by means of specific Y. enterocolitica O9 and Brucella melitensis immunoreagents in rabbits immunized with Y. enterocolitica were absent during the first days and could be detected only of day 25 after the injection of the immunogen. The method for the detection of ABL with the use of newly developed reagents could be used in clinics for the diagnostics of intestinal yersiniosis.