The author reports for the first time on a case of pseudotuberculosis in a boy aged 9 years in the Karelian ASSR. The disease was diagnosed in the course of a histological investigation of the bioptic specimen of the mesenteric lymphatic node obtained during the operation performed in connection with suspected appendicitis. Histologically there were revealed granulomas with microabscesses therein and around them--very small foci of necrosis and necrobiosis with a positive reaction to fibrin. Granulomas, in contrast to those described in the literature, consisted predominantly of epithelioid, but not of reticular, cells. Their nuclei were poor in DNA, whereas cytoplasm--in RNA and Schick-positive material. Along the periphery of many granulomas there was revealed a zone of reticular cells with markedly pyroninophil cytoplasma (with plasmatization). In the cytoplasma of leukocytes a considerable amount of glycogen was identified.