Fibromyalgia syndrome (FMS) is characterized by chronic widespread musculoskeletal pain, stiffness and tenderness at multiple points. Sleep disturbances are common in FMS and patients usually complain about nonrestorative sleep. Obstructive sleep apnea syndrome (OSAS) is characterized by repetitive pharyngeal collapse during sleep. Recurrent arousals from sleep occurs to restore pharyngeal patency in OSAS and this results in increased sympathetic activity and fragmentation of sleep. Sleep disturbances may lead to musculoskeletal pain and some studies suggest a relation between OSAS and FMS. Since OSAS is strongly associated with increased risk of myocardial infarction, cerebrovascular accidents and congestive heart failure, its diagnosis and treatment are of particular importance. Herein we present a female patient with diagnosis of FMS for 10 years who had complaints of morning fatigue, restless sleep, sleepiness during day and snoring besides musculoskeletal symptoms. Severe OSAS was diagnosed after polysomnographic analysis and FMS symptoms were totally improved with nasal continuous positive airway pressure treatment.