Here, we describe the case of a 51-year-old female with mediastinal liposarcoma. Liposarcoma is the most common malignant mesenchymal neoplasm in adults, although a mediastinal location is extremely rare. It has a large volume and varied histologic subtypes. It is characterized by the compression of neighboring structures. Computed tomography and magnetic resonance imaging provide useful data for diagnosis. Tissue biopsy and histological typing are very important in determining the treatment and are needed for the final diagnosis. Radiotherapy and chemotherapy are ineffective treatment modalities. According to the literature, surgical resection is the treatment of choice. Long-term follow-up evaluation is indicated since there is a high rate of recurrence.