Two cases of gastric leiomyosarcoma diagnosed by ultrasound are presented. Upper abdominal sonogram discloseda large lobulated echogenic mass containing a few or multiple anechoic fluid-filled spaces in each cases. Theseanechoic spaces were confirmed to be necrotic or hemorrhagic cavities in the solid mass pathologically. Theauthors wish to emphasize thse echopatterns are characteristic of mesenchymal tumor, such as leiomyoma orleiomyo-sarcoma, in particular.