The inferior mesenteric vein is an upward continuation of the superior rectal vein. It ascends behind the peritoneum lateral to the inferior mesenteric artery. Afterward it enters lateral to the duodenojejunal flexure and anterior to the left renalvein to terminate by joining the splenic vein supporting the pancreas. It might deviate to the right and join the superior mesenteric vein or its junction together with the splenic vein.

The tributaries of the inferior mesenteric vein correspond to the branches of the inferior mesenteric artery.