Patients undergoing splenectomy have an increased risk of splenic/portal vein thrombosis. We used several databases to identify publications dealing with this risk and analyzed incidence, risk factors and outcome. The risk of splenic portal vein thrombosis has been addressed in prospective and retrospective randomized or non-randomized studies. All studies combined, the overall risk is 3.3%. Risk factors are big spleens (i.e. myeloproliferative disorders) and hereditary hemolytic anemias, whereas the risk is low in autoimmune thrombocytopenia and trauma. The incidence is approximately the same in laparoscopic and open splenectomy. The median time from splenectomy to symptomatic splenic vein thrombosis is 8-12 days. Postoperative antithrombotic prophylaxis ranged from no prophylaxis to heparin for seven days or longer. Treatment of symptomatic splenic vein thrombosis with heparin and warfarin leads to complete resolution of thrombosis in 67%, to partial resolution in 13%, but persistent occlusion, portal hypertension or cavernoma occurred in 20%.The long-term outcome of treatment failures is unknown. Well-designed randomized studies on the prophylaxis of venous thromboembolism after splenectomy are urgently needed.