Portal vein thrombosis (PVT) following splenectomy is a potentially life-threatening complication, and the true incidence of PVT in splenectomized patients is unknown. The objective of this study was to determine the incidence of symptomatic PVT after splenectomy. The hospital database was searched to identify cases of PVT associated with splenectomy from January 1990 to May 2002. Six hundred eighty-eight patients underwent splenectomy during this period, 321 of them for hematologic diseases. Eleven of the 688 patients had PVT associated with splenectomy, and the charts of these patients were reviewed. Six patients developed PVT after splenectomy. Five had hematologic diseases. Symptoms were abdominal pain (6), ileus (5), fever (3), or diarrhea (2). Diagnosis was confirmed by computed tomography (CT) (4), duplex ultrasonography (1), and magnetic resonance imaging (1). The indications for splenectomy included hemolytic anemia (3), thalassemia (1), and myelofibrosis (1). One patient had an incidental splenectomy during gastrectomy. There were four laparoscopic and two open splenectomies. The median interval between splenectomy and diagnosis of PVT was 40 days (range, 13-741). One patient died of pulmonary embolism. Five of six patients with postsplenectomy PVT had splenomegaly and hemolysis. We conclude that the risk of PVT is higher in patients with hematologic conditions associated with splenomegaly and hemolysis.