Uterine leiomyosarcoma (LMS) represents a rare tumor, accounting for 1.3% of all uterine malignancies. Although this tumor shares morphological and clinical features with other uterine benign and malignant tumors, the accurate diagnosis is necessary, due to their different biological behavior and prognosis. Therefore, we present a case of LMS in a 48 year-old patient, complaining of a 3-months metrorrhagia. The tumor presented as a poorly defined submucosal nodule, with a soft consistence and measuring 6 cm in diameter. The microscopic examination of this tumor nodule revealed fascicles of spindle cells, with pleomorphic hyperchromatic nuclei exhibiting moderate to severe atypia and areas of tumor necrosis. At least 5 atypical mitoses/ 10 HPF were also found. Immunohistochemistry technique, with a panel of six antibodies, comprising ER, PR, PCNA, SMA, p53, and bcl-2, has been performed for the differential diagnosis. The final histopathological diagnosis was that of uterine LMS. Considering LMS an aggressive tumor, the patient has been recommended a thorough follow-up.