Uterine leiomyosarcoma (uLMS) is a rare entity among malignant gynecologic tumors with a very unfavorable prognosis and the highest prevalence in the pre- and peri-menopause. Only early-stage tumors have an acceptable prognosis, provided the patient has been treated without injuring the uterus. uLMS is often diagnosed accidentally and the correct diagnosis ishampered by equivocal features similar to the far more frequent benign uterine fibroids. Surgery is the basis of therapy, and it should be done in order to remove the uterus intact. As vaginal, abdominal, and endoscopic surgery - possibly including morcellation - are the methods of choice for the treatment of uterine fibroids, pre-operatively undiagnosed leiomyosarcoma detected by pathologic examination will have a worsened prognosis. Systemic treatment and radiotherapy are of no proven value in the adjuvant setting. Thus, there is strong need for a reliable pre-operative risk score for leiomyosarcoma in order to justify diagnostic means beyond clinical routine and to choose the correct surgical pathway. The clinical problems in the diagnosis of leiomyosarcoma and treatment are exemplified by a case report of a 30-year-old childless patient. Diagnostic tools as well as treatment options in adjuvant and palliative situations are reviewed.