Abnormal sensory responses have been found in the upper airway of obstructive sleep apnea patients, but no long-term study has been published previously regarding the evolution of obstructive sleep apnea syndrome and persistence of abnormal pharyngeal sensory evaluation in response to continuous positive airway pressure (CPAP) treatment. Over 5 years, we managed healthy, nonobese subjects compliant with nasal CPAP. Only 47 subjects completed this prospective study, due to protocol requirements. They underwent regular clinical evaluation, subjective scales, four polysomnographies without nasal CPAP, recalibration of nasal CPAP with polysomnography, regular downloading of home data, and a palatal two-point discrimination study. None of the subjects presented normal results at any checkpoint when they had been without CPAP for two or three nights. By the completion of the study, all subjects required an increase in nasal CPAP (1-7cm H2O) and demonstrated abnormal two-point palatal discrimination compared with control subjects. Despite initial control of clinical symptoms with regular usage of nasal CPAP in subjects without weight change, abnormal sensory palatal evaluation was present at the conclusion of the study. Obstructive sleep apnea syndrome involves abnormal upper airway sensory input, which may be responsible for the development of apneas and hypopneas. These neurological lesions are persistent despite nasal CPAP treatment.