In an attempt to determine the relationship, if any, between the size of the splenic artery and various clinical aspects of splenic vein thrombosis, including splenomegaly, the clinical and angiographic findings in ten patients with this disorder were reviewed. The size of the splenic artery was found to be unrelated to the nature of the underlying disease, age of the patient, or history of variceal bleeding. An abnormally wide and tortuous splenic artery was identified only in those patients (five) in whom there was also radiographic evidence of splenic enlargement. Since the angiographic finding of an enlarged and tortuous splenic artery is known to correlate closely with increased flow in this vessel, this observation suggests that in patients with isolated splenic vein obstruction an increase in splenic artery flow accompanies splenic enlargement and is probably a critical component of the underlying derangement.