A review of the surgical and autopsy records from two general hospitals in La Paz, Bolivia, discloses an incidence of colon and rectal disease, excluding hemorrhoids, of 0.6 per cent (138 of 22,361 surgical cases) and 2.5 per cent (16 of 640 consecutive autopsies). Acquired megacolon complicated by volvulus represented more than half of all cases in the surgical series. Ulcerative colitis, diverticular disease, and neoplastic polyps represented less than 10 per cent of the cases of colonic diseasce. Only ten cases of carcinoma of the colon were seen, whereas five cases of granulomatous colitis or ileocolitis were detected in the same surgical material. Among sixty-four lesions of the rectum, so-called retention polyps accounted for 54.5 per cent of the cases, with carcinoma next in frequency (25 percent), and the remainder being different varieties of inflammatory conditions. In the autopsy material almost half of the cases were infectious conditions, followed by congenital malformations and complicated acquired megacolon. No case of diverticular disease of the colon or neoplastic polyps was seen, and there was only one case of cancer of the large bowel. Because of the high incidence of acquired megacolon and the low incidence of cancer, ulcerative colitis, adenomatous polyps, and diverticular disease of the colon, possible etiopathogenic factors of these conditions are discussed in comparison with their incidence in other developed and developing countries of the world.