Obstructive sleep apnea syndrome (OSAS) is characterized by multiple episodes of upper airway (UA) obstruction during sleep. Patients experience daytime hypersomnia, sluggishness and inability to concentrate; snoring at night is common. We report the case of a man with Hodgkin's lymphoma without full remission and with pharyngeal recidivism leading to OSAS. He experienced marked diurnal hypersomnia accompanied by behavior disorders. Examination revealed flow-volume OSAS, suggesting UA instability. Cervical computed tomography showed a prevertebral lymphomatous mass in the pharynx causing significant UA compression. UA size increased considerably after use of continuous positive airway pressure (CPAP), which normalized sleep and produced significant relief of symptoms. Later, after chemotherapy, OSAS resolved and the patient was able to abandon CPAP treatment.