Mesenterico-portal venous thrombosis following hematological splenectomy is infrequent. We report about three cases successfully treated with heparin. A review of the literature allows identifying three factors acting in the etiopathogenesis of such thrombosis: alteration of blood composition, blood stasis and injuries to the vascular walls. The diagnosis is confirmed by ultrasonography and abdominal CT, and echo-Doppler will play a more important role in the future. The treatment of mesenterico-portal thrombosis is mainly medical, with surgery being indicated only in case of intestinal necrosis. An anticoagulant or platelet-suppressive treatment and the ligation of the splenic vein as close as possible to its junction with the mesenteric vein may be proposed as preventive measures.