Smooth muscle tumors of the mesentery are rare lesions with unpredictable, usually malignant, biologic behavior irrespective of their histologic appearance. Such case is presented here. We present a case of a large smooth muscle tumor located in the mesentery of a 48 years old patient. The histopathologic features of the surgically excised tumor were that of a benign-appearing smooth muscle tumor, either a primary mesenteric smooth muscle tumor of unknown biologic behavior or a parasitic leiomyoma. The patient was discharged 4 days after from the hospital without any early postoperative complication. Close followup was further decided. Nine months after her primary therapy, our patient is alive and with no evidence of recurrent disease. Increased awareness must be considered for large mesenteric smooth muscle tumors, because even when they present indolent histologic features, they usually behave aggressively.