In recent years the tendency to think of tuberculosis as a common cause of multiple ulcers in the rectum and sigmoid has lessened. This has come about because of a better knowledge of the lesions of chronic ulcerative colitis and amebiasis associated with ulceration. That some confusion still exists is evident, however, as patients having chronic ulcerative colitis are often diagnosed as having tuberculous enteritis, particularly if they happen to be emaciated. However, the gross lesions of tuberculosis, chronic ulcerative colitis and parasitosis in the large bowel have several distinct differences. It is of practical value to emphasize that, outside of institutions for the tuberculous, tuberculous ulcers of the rectum and sigmoid are infrequently observed and that chronic ulcerative colitis and amebiasis with ulceration are the more common lesions seen in ordinary practice. As the characteristic appearance of the colon ulcers in these three diseases is becoming better known, it