Five cases of exophytic gastrointestinal leiomyosarcoma were evaluated by sonography. In 3 of the 5 cases, identification of intraluminal air or intestinal lumen in an eccentric location to the mass was helpful in recognizing the exophytic nature of the mass. Tumor necrosis was present in all of the masses and also in 1 case of hepatic metastasis. Recognition of the exophytic nature of the mass and the presence of tumor necrosis favor the diagnosis of leiomyosarcoma.