In 114 cases of the transverse colon isolated from cadavers (50 male, 64 female), anatomical examinations of the arterial system of the colon were performed. Arteriograms were obtained after dissecting and contrasting the colonic vessels with Mixobar contrast. In one case, on arteriography of the colon with its mesentery isolated from a 55-year-old male cadaver, a rare anatomical variant was found. The third mesenteric artery originated directly from the aorta-halfway between the superior and inferior mesenteric arteries and ascended obliquely in the direction of the hepatic flexure of the colon. Supply area of the artery was typical for the middle colic branch of the superior mesenteric artery: the distal segment of the ascending colon and the transverse colon. Such a variation, although very rare, may have particular impact on diagnosis and even the method and range of surgery.