Objectives:To describe the prevalence of sleep-disordered breathing (SDB) in Chilean schoolchildren and study associated risk factors. Patients and Method: We carried out a transversal and descriptive study. Questionnaires were sent to the parents of children attending first year of elementary school in the Metropolitan Region (Santiago), the Biobío Region (Concepción, Chillán, Yumbel) and the Magallanes Region (Porvenir and Puerto Natales). Anthropometric data, school performance, household characteristics, indoor pollutants, medical history, and current symptoms of asthma, allergic rhinitis, and atopic dermatitis were recorded. The nutritional status was determined according to z-BMI. A pediatric sleep questionnaire validated in Spanish (PSQ) was applied. Results: 564 questionnaires were analyzed, the median age was six years (range 5 to 9), 44.9% male. The SDB prevalence was 17.7% (n = 100): 6% in Vitacura (Metropolitan Region), 28.7% in Chillán (Biobío Region), and 36.4% in Puerto Natales (Magallanes Region) (p = 0.001). The group with SDB had a higher proportion of men (54.5 vs 42.8%, p = 0.033), lower academic performance (overall grade point average 6.36 ± 0.48 vs 6.56 ± 0.34, p = 0.001), lower maternal higher education (44.4% vs 69.9%, p = 0.001), and higher exposure to indoor pollutants than those without SDB. After the multivariate analysis, symptoms of rhinitis in the last 12 months (OR 4.79,) and lower maternal educational level (OR 3.51; 95% CI 1.53-8.02) remained as predictors of SDB. Conclusions: Chilean schoolchildren have a high prevalence of SDB with demographic differences. It was associated with social risk factors, more specific factors of lung damage, and worse sleep quality and quantity.