To evaluate a possible brainstem role in pathogenesis of obstructive sleep apnea syndrome, a study on brainstem auditory evoked potentials (BAEP), has been conducted. 15 OSAS patients, medium and severe form, with organic pathologies of the upper respiratory tract have been evaluated. 15 normal subjects were compared as control. All the patients were subjected to audiometry, including total liminal audiometry, timpanometry, acustic reflex, and BAEP study. BAEP evoked with trains of cliks at 11 and 51 periods/sec., showed morphological alterations and a longer central conductance of time interval (I-V interval) in only four patients. BAEP alterations noted in the OSAS-affected patients are neither constant nor specific. Therefore, the observed BAEP alterations might be due to apneas, as a consequence of the chronic hypoxic- hypercapnic status occurring in the brain-stem.