Introduction, The reciprocal influence between Epilepsy and Sleep Apnea Syndrome (SAS/OSAS) may aggravate the prognosis of both processes. Hypoxemia during sleep inpatients with SAS and sleep fragmentation as a consequence of periodic apneas, that provokes a chronic sleep deprivation, could decrease the convulsive threshold ill epileptic patients. Material and methods. We have carried out a descriptive and retrospective study in 20 patients with epilepsy and SAS, of which EEG recordings, video-polysomnography (PSG) and nocturnal oximetry were available. Results. 90% were males. 75% had partial epilepsies and 25% generalized The mean duration of epilepsy was 14.5 years. The mean seizures frequency was one per month. 35% had nocturnal seizures, 15% diurnal and 50% of the patients had diurnal and nocturnal seizures. Other symptoms associated with seizures were: Snoring (100%), daytime sleepiness (70%), nocturnal respiratory pauses (30%), arterial hypertension (30%), overweight (25%) and morning headache (15%). The PSG showed epileptic interictal discharges in 95% of the cases, focal in 80%, and a disturbance of the sleep architecture, with a decreased sleep efficiency and continuity. The mean hypopnea-apnea index was 38. Conclusions. The association Epilepsy-SAS in adult patients affected of localized epilepsy, with risk factors for SAS (male gender, obesity, snoring, adverse effects of drugs) must be taken into account and a video-PSG-oximetric study is indicated to confirm it. It should be noted that anticonvulsant therapy could cause breathing dysfunction during sleep or aggravate a pre-existing or latent SAS. It be expected that the satisfactory treatment of SAS could improve the control of the seizures in these patients.