Fifty-two men (aged 41-50 years) of whom 25 reported habitual and 27 of occasional or never snoring were examined clinically. Whole-night sleep recordings of body and breathing movements, snoring and blood oxygen saturation were made. Hypoxic events exceeding 4% from the baseline were counted. Ninety-three percent of those classified snorers by the recordings were habitual or occasional snorers, but 50% of those similarly classified non-snorers had reported habitual or occasional snoring. Four habitual snorers had abnormal breathing indices and polysomnography established obstructive sleep apnea syndrome (OSAS) in one. Thus, self-reported habitual snoring is a reliable OSAS-screening method. Estimated prevalence of OSAS based on this study is 0.4-1.4%. In multivariate regression analysis, the hypoxic events were explained by obesity and apneic events. The diastolic blood pressure level was best explained by obesity, but not hypoxic or apneic events or snoring history.