A patient with splenic arteriovenous fistula associated with portal vein hypoplasia, presenting as hypersplenism, is reported on herein and reports of eight other cases of splenic arteriovenous fistulas are reviewed. The diagnosis in our patient was not made until operation, when the fistula was excised, the spleen removed, and a splenorenal shunt performed. The intrasplenic arterial tree showed numerous aneurysms at the bifurcation of the vessels supporting the congenital nature of the lesions. Catheterization of the vena azygos major was successfully performed before operation and the oxygen saturation of the sample obtained found to be unusually high. These results were not interpreted correctly but believed to support the possibility of shunting of portal venous blood into the azygos system.