Paroxysmal nocturnal hemoglobinuria is a rare disorder characterized by pancytopenia. One of the main manifestations of this disease is development of widespread life-threatening venous thrombosis, which may involve multiple abdominal veins. We describe two patients with paroxysmal nocturnal hemoglobinuria with clinically unsuspected portal, splenic, and mesenteric venous thromboses that were diagnosed on computed tomography. This complication should be clinically suspected in patients suffering from paroxysmal nocturnal hemoglobinuria who present with abdominal pain, and it should be sought by the radiologist on pre- and postcontrast computed tomography.