The role of the human ileocolonic junction in the transit of solid contents through the entire gut was evaluated. Eight patients, well compensated after right hemicolectomy for localized colon cancer, and eight age-matched healthy controls were enrolled. Scintigraphic transit was quantified after subjects ingested a mixed meal containing 111In-labeled Amberlite beads (average diameter, 1 mm; Sigma Chemical Co., St. Louis, MO). Gastric emptying was initially faster in the postoperative group, but overall emptying was not different from controls; small bowel transit also did not differ between the groups. In patients in whom the distal ileum, ileocolonic sphincter, and proximal colon were absent, isotopes moved from small to large bowel in a manner that was qualitatively and quantitatively no different from that of controls. Major episodes of coloileal reflux could not be identified in either group. After hemicolectomy, the residual transverse colon, and to a lesser degree the descending colon, were able to store solid residue, although in lesser amounts than the unoperated large bowel. The ileocolonic sphincter in humans appears to play only a minor role, at most, in ileocolonic transit, and the colon remaining after right hemicolectomy stores residue so that bowel habits are not greatly disturbed.