Five hundred and eighty persons who were heavy snorers filled in a questionnaire regarding symptoms on a 5-grade scale. Of these, 178 had a complete polysomnography investigation while 402 patients underwent oxymetric screening during the night only. On the basis of these investigations. 217 were classified as suffering from the obstructive sleep apnea syndrome (OSAS) and 363 as snorers without OSAS. The symptom scores differed between the two groups, but the range was wide and some persons with OSAS claimed only minor daytime sleepiness, somnolence, etc., while a high proportion of persons without OSAS frequently suffered from such symptoms. Thus, it was not possible to discriminate between patients with and without OSAS on the basis of their symptoms only. Furthermore, there are many persons who are "only" heavy snorers but who have symptoms that affect their career and social life and who so far have only received scant interest from the medical profession. Excessive daytime sleepiness and somnolence thus do not seem to be secondary to hypoxemia at night but rather to poor quality of sleep, which may be the case in association with heavy snoring even without appreciable deterioration of oxygen saturation.