Although previous studies demonstrated that patients with obstructive sleep apnea syndrome (OSAS) may present subclinical manifestations of dysphagia, in not one were different textures and volumes systematically studied. The aim of this study was to analyze the signs and symptoms of oropharyngeal dysphagia using fiberoptic endoscopic evaluation of swallowing (FEES) with boluses of different textures and volumes in a large cohort of patients with OSAS. A total of 72 OSAS patients without symptoms of dysphagia were enrolled. The cohort was divided in two groups: 30 patients with moderate OSAS and 42 patients with severe OSAS. Each patient underwent a FEES examination using 5, 10 and 20 ml of liquids and semisolids, and solids. Spillage, penetration, aspiration, retention, and piecemeal deglutition were considered. The penetration-aspiration scale (PAS), pooling score (PS), and dysphagia outcome and severity scale (DOSS) were used for quantitative analysis. Each patient completed the SWAL-QOL questionnaire. Forty-six patients (64 %) presented spillage, 20 (28 %) piecemeal deglutition, 26 (36 %) penetration, and 30 (44 %) retention. No differences were found in the PAS, PS, and DOSS scores between patients with moderate and severe OSAS. Patients with severe OSAS scored higher General Burden and Food selection subscales of the SWAL-QOL. Depending on the DOSS score, the cohort of patients was divided into those with and those without signs of dysphagia. Patients with signs of dysphagia scored lower in the General Burden and Symptoms subscales of the SWAL-QOL. OSAS patients show signs of swallowing impairment in about half of the population; clinicians involved in the management of these patients should include questions on swallowing when taking the medical history.