The article describes a case of a rare infection caused by Yersinia pseudotuberculosis in a five-year-old boy admitted to the hospital. The infection was manifested by the so-called right lower quadrant syndrome, or terminal ileitis. The Y. pseudotuberculosis strain was isolated from the patient's feces and its biochemical properties are reported. Confirmation was performed by the National Reference Laboratory for E. coli and Shigella. Since pseudotuberculosis is very rare in the Czech Republic, the authors would like to draw attention to this infection. Enlargement of lymph nodes in the right lower quadrant of the abdomen may suggest the infection caused by Y. pseudotuberculosis.