Electron microscopic examinations of biopsy specimens of the large intestine from 8 patients one month after termination of the acute phase of dysentery revealed dystrophic and destructive changes in surface epithelium cells consisting in the lack of glycocalyx, fragmentation of microvilli, vacuolation and subsequent homogenization of the cytoplasm. Swelling and destruction of mitochondria, pyknosis and rhexisof the nucleus, exposure and loss of the intactness of the apical membrane of the cells were observed. The altered colonocytes frequently became detached off the basal membrane, exposing the stroma. The results of the study attest to long-term persistence of both the pathological and infectious processes in protracted forms of Shigella infection in man.