ALTHOUGH DIVERTICULA of the small intestine commonly reach a diameter of several centimeters, it is rare for those involving the colon to reach a size greater than 1 to 2 cm in diameter.1A small number of true giant diverticula of the large bowel, however, have been reported in the literature.2-6All of these cases involved the sigmoid colon, with diverticula ranging from 10 to 25 cm in diameter, and were associated with smaller adjacent diverticula. A definite communication between the cyst and lumen of the bowel could be demonstrated in four of the five cases, but was large enough to permit barium filling on roentgenologic examination in only one patient. Duplications of the alimentary tract, which at times have been misnamed "giant diverticula," represent the main entity to be differentiated pathologically from true air-containing diverticula. The former are spherical or tubular structures which possess a well-developed smooth-muscle