Superior mesenteric venous occlusion may be difficult to recognize, but is important as it carries a better prognosis than superior mesenteric arterial occlusion, an may be amenable to surgical treatment. Three cases of primary superior mesenteric venous occlusion are described. The diagnosis was unsuspected until discovered at laparotomy. Non-viable bowel was present in all cases and in two cases thrombosed veins were apparent in the mesentery. The lesion was localized in distribution, and generous bowel resection with primary anastomosis was performed. Recovery was uncomplicated in all cases. When the thrombosis appears well localized, generous resection with primary anastomosis seems a suitable alternative to resection and exteriorization or conservative treatment with a second-look procedure.