Objective.-To find out whether there is a relationship between the headache characteristics and polysomnographic findings in patients with prediagnosis of the sleep apnea syndrome (SAS) and, if there is, to search for its possible cause. Background.-Chronic morning headache is considered by many to be an important part of the SAS. Some reports support this relationship, and some do not. Methods.-We questioned 75 patients with SAS about headache. Headaches were classified according to the International Headache Society (IHS-88) system. We evaluated the relationship between headache and polysomnographic findings. Results.-There was no statistically significant relationship between headache and apnea hypopnea index (AHI) or minimal oxygen saturation ( P > .05). Conclusions.-We could not demonstrate a statistically significant relationship between headache, AHI, and minimal oxygen saturation in our patients with SAS.