The liver, skeletal muscle, and adrenal gland obtained from two nine-banded armadillos infected with Mycobacterium leprae were studied using an electron microscope. M. leprae were found in varying numbers inside hepatocytes, Kupffer's cells, striated muscle cells, adrenal cortical and adrenal medullary cells, endothelial cells, and macrophages. There was evidence to suggest that M. leprae were actively phagocytosed by the liver and skeletal muscle cells. The inert nature of M. leprae and its behavior as an almost ideal parasite of parenchymal cells are emphasized. The question of whether this unique parasitism of parenchymal cells and the possible processing and presentation of M. leprae antigens by these cells could be responsible for aberrant immune responses is raised.