Leiomyosarcoma of the stomach is an unfrequent tumor, for which the prognosis is better than for cancer of the stomach. Its development is often subserosal, thus explaining its clinical latency and its large volume at the time of diagnosis. While many publications report about the merits of conventional imaging for this type of pathology, few authors have considered ultrasonographic endoscopy, and even fewer magnetic resonance imaging. The authors present one case for which these two recent techniques were implemented, as well as a review of the literature.