Objective: To follow a cohort of children from age 4-6-12 with respect to sleep disordered breathing (SDB) and orofacial development. Questionnaires were completed about sleep, snoring, apneas, enuresis, sucking habits, and adenotonsillar surgery and, from age 12, about allergies, asthma, and general health. Children snoring regularly had an ENT- examinations including sleep studies (at ages 4 and 12) and an orthodontic evaluation. Development of biometric data in snoring children and not snoring controls was studied in relation to adenotonsillar surgery. Result: Of the original group of 615 children, 509 (83%) participated at age 6 and 393 (64%) at age 12. 27 snored regularly and 231 did not snore at age 12. Differences between groups were seen on all answers. From age 4–12 the prevalence of OSA decreased from 3.1% to 0.8%, and the minimum prevalence of snoring regularly from 5.3% to 4.2%. The odds for a child who snored regularly at four or six to be snoring regularly at age 12 was 3.7 times greater than for a not snoring child in spite of surgery (OR 3.7, 95% CI 2.4-5.7). 63 children were operated for snoring by age 12, of them 14 never snored and 17 snored regularly at age 12. Cross-bite was more common among snoring children at ages 4, 6 and 12 as was a narrower maxilla. In most cases, surgery cured the snoring temporarily, but the maxillar width was still smaller by age 12—even when nasal breathing was attained. Children snoring regularly at age 12, operated or not operated, showed long face anatomy and were oral breathers; the seven cases who were not operated and the five who were still snoring in spite of surgery, did not have reduced maxillary arch width. Conclusion: The prevalence of children snoring regularly is about the same from age four to twelve in a cohort where adenotonsillar surgery has been performed on obstructed cases, but the prevalence of OSA decreases considerably. The children snoring regularly have a more narrow maxilla compared to children not snoring—a condition that is not changed by adenotonsillar surgery regardless of symptom relief.