The majority of gastrointestinal sarcoma is gastrointestinal stromal tumors and intestinal leiomyosarcoma is rare. Small intestinal mesenchymal tumors are often large at diagnosis, and they commonly present with bleeding or intussusception. We report a perforation associated with intestinal leiomyosarcoma. METHODS A 66-year-old man presented with severe epigastric pain. A physical examination showed tachycardia and a diffusely tender and rigid abdomen. Computed tomography showed a massive tumor and free air. A laparotomy was performed to treat lower digestive perforation. Massive tumor, which invaded surrounding intestine, was 20 cm in size at the ileum. The involved intestine was perforated. We confirmed that feeding artery was superior mesenteric artery and performed partial intestinal resection. His clinical course was uneventful and discharged 10 days postoperatively. The pathological findings showed spindle shaped and the tumor invaded the mucosa at the perforated site. Immunohistochemical spectrum resulted c-kit negative, S-100 negative, Desmin positive, alpha smooth muscle actin(αSMA) positive and Ki-67 30-40 %. The pathological findings were leiomyosarcoma. CONCLUSIONS Gastrointestinal sarcoma is sometimes found by bleeding. In our patient, leiomyosarcoma invaded surrounding intestine, it made the intestine wall frail and caused perforation. The intestinal perforation which was involved by leiomyosarcoma has been rarely reported to the best of our knowledge since WHO refined leiomyosarcoma. CONCLUSIONS Although intestinal leiomyosarcoma is rare, we should know that it can involve surrounding intestines and make them perforated.