We report herein the case of a 63-year-old male with hemoperitoneum secondary to exogastric leiomyoma. The patient had been receiving anticoagulation therapy for a cerebral embolism and complained of sudden, severe abdominal pain. A sonogram and computed tomography scan showed an exogastric mass and massive ascites. A peritoneal puncture proved the presence of an intraperitoneal hemorrhage. An emergency laparotomy revealed a pedunculated bleeding tumor, thus confirming the preoperative diagnosis of a ruptured exogastric tumor. A microscopic analysis of the excised tumor demonstrated gastric leiomyoma. Other authors have reported hemoperitoneum secondary to gastric myogenic tumors, but no cases of leiomyomas could be found in the literature.