Morphologic study of the lungs, liver, spleen, and kidneys of ferrets infected with canine distemper virus has been carried out. Electron microscopy revealed virus reproduction in bronchial epithelial cells, types I and II alveolocytes, bile duct epitheliocytes, and hepatocytes. Mononuclear phagocyte system cells infected with the virus were found in all the examined organs. The most expressed pathological changes were observed in the lungs.