We present a 42-year-old female admitted for a 4 month history of increasing pelvic discomfort and pain. Clinical examination revealed a large tumor obstructing the vagina. Tumor markers (CA 125, CEA, AFP and CA 19-9), white blood cells and biochemical tests were all within the normal limits. Pelvic ultrasound and magnetic resonance imaging scan confirmed the presence of a large retroperitoneal/pelvic mass. The tumor was surgically excised and pathohistologically diagnosed as a well differentiated leiomyosarcoma, staged IB. Six years after surgery the patient is well and disease free.