Our objective was to investigate the prevalence of sleep-disordered breathing (SDB) and obstructive sleep apnea syndrome (OSAS) in 3-11-year-old Turkish children. A cross-sectional study was conducted in Zonguldak, northwestern Turkey Symptomatic children were identified by using a self-administered questionnaire and were classified into three groups: nonsnorers, occasional snorers, and habitual snorers. All habitual snoring children were invited to undergo polysomnography (PSG). Nine hundred fifty-four children (79.5%) were nonsnorers, 205 (17.2%) were occasional snorers, and 39 (3.3%) were habitual snorers. There was no significant relationship between gender and habitual snoring (male, 3.4%; female, 3.1 %; P > 0.05; odds ratio (OR), 1.13; 95% confidence interval (CI), 0.59-2.14). There was a statistically significant relationship between habitual snoring and allergic rhinitis (OR, 4.23; 95% Cl, 2.14-8.35). Fourchildren who snored every night, and who had apnea spells and/or troubled sleep, underwent adenoidectomy and/or tonsillectomy before polysomnographic evaluation because of clinical detoriation. Twenty-eight of 39 children with habitual snoring participated in PSG evaluation. PSG revealed that 11 children (0.9% of the total population) had OSAS. When 4 operated children were added to these 28 children, we found the minimum prevalence of OSAS to be 1.3% in our study group. There was a significant correlation between OSAS and troubled sleeping (P < 0.001; OR, 4.37; 95% Cl, 1.33-14.3). We found the prevalence of habitual snoring to be 3.3% in Turkish children by using self-administered questionnaires. Allergic rhinitis was significantly correlated with habitual snoring. Minimum estimated prevalence of OSAS was found to be 1.3%. (C) 2005 Wiley-Liss,lnc.