A through knowledge of the anatomy of colonic mesenteric arteries is necessary to accomplish successful, uncomplicated abdominal operations, especially laparoscopic colonic resections in which the mesenteric vessels can't be palpated. Such knowledge is also important when performing a colonic resection for cancer using proximal vascular ligation and wide en bloc resection. Most surgical textbooks depict a "normal pattern" of arterial supply to the right colon as consisting of three arterial branches (the ileocolic, the right colic, and the middle colic arteries) arising independently from the superior mesenteric artery (SMA). Based on the literature, there are only two colonic arteries arising independently from the SMA in many cases. We examined the anatomy of these arteries in 50 patients who had had SMA angiographies for various diseases from January 1995 to May 1997. In all of our cases, the ileocolic artery and the middle colicartery emanated directly from the SMA, but the right colic artery originated directly from the SMA in only 54% of the cases. The right colic artery was absent in 8% of the cases. It also arose as a single trunk with the middle colic artery (22% of the cases) and from the ileocolic artery (16% of the cases). Our data, together with published anatomic studies, lead us to conclude that in many cases there are only two independent branches arising from the SMA that supply the large intestine, the ileocolic artery and the middle colic artery. This knowledge may be helpful in laparoscopic colon surgery, radical colon resections for cancer, and colon replacements after operations on the esophagus or the urinary bladder.