Four asymptomatic cases are reported of aneurysms of the spleno-portal and measenteric veins. These ectasias, whose ethiology is most probably congenital, are very rare (about 20 cases in world literature), especially if compared with aneurysms of the splenic arteries, and they are mainly occasional findings. Complications may occur in the biliary tract and duodenal loop, often associated with portal hypertension. US and CT are sometimes very valuable in characterizing them, but an angiographic map is needed for the patients who will undergo surgery. Angiographic procedure is also mandatory for interventional approach in case of porto-caval fistulas. Doppler US scanning seems to be the best technique for the follow-up.