Sarcomas of the head and neck are relatively infrequent tumors. Liposarcomas represent 10-16% of all soft tissue sarcomas and <5% of them arise from the head and neck. The retropharyngeal area is rarely involved. We present the case of a middle-aged male with clinical symptoms of sleep apnea. A fiber-optic examination revealed a soft submucosal lesion compressing the posterior pharyngeal wall, with partial obstruction of the airway tract. CT showed a large heterogeneous prevertebral mass (620 cm²) occupying the posterior mediastinum. A transoral submucosal biopsy was performed. Histological findings were compatible with a low-grade liposarcoma. The mass was removed in monoblock using a classical laterocervical neck incision. The surgical specimen weighed 500 g. After 24 months of follow-up no signs of tumor recurrence or sleep apnea syndrome were noted.