A 77-year-old man with a history of multiple surgically treated malignancies presented with increasing abdominal pain after eating. Computerized tomographic scan showed superior mesenteric vein and portal vein thrombosis. The patient was treated with selective superior mesenteric artery infusion of urokinase resulting in clinical improvement and near complete resolution of the mesenteric venous thrombosis. An underlying gastric malignancy was found and is believed to be the cause of the patient's hypercoagulable state. Direct infusion of urokinase into the superior mesenteric artery for treatment of mesenteric venous thrombosis is an alternative to surgery in selected patients and an alternative to the much more complicated delivery systems presently used.