Sarcoma of the stomach is a rare histological entity. These differentiated mesenchymal tumors do not differ clinically from other gastric cancers. Endoscopic ultrasonography is the preferred means of exploration because it determines the existence of a submucosal lesion and provides guidance in determining its type. Certainty of diagnosis requires pathologic and immunohistochemical examinations of the surgical specimen. Malignant gastric stromal tumors are the first differential diagnosis of sarcoma of the stomach. They can be better characterized by testing their expression of the c-kit protein. Histological confirmation of malignancy sometimes remains difficult. Locoregional invasion and distant metastases confirm malignancy. Treatment is essentially surgical. Prognosis depends on tumor size, extension, rupture and histological grade.