It is not known whether children with primary snoring (PS) progress to develop obstructive sleep apnea syndrome (OSAS). Therefore, we repeated polysomnography in a cohort of 20 children diagnosed 1-3 years previously with PS. All children initially presented with symptoms suggestive of OSAS. They were diagnosed with PS when initial polysomnography demonstrated snoring, with less than one obstructive apnea per hour, normal gas exchange, and infrequent arousals. Of 75 potential candidates, 20 were available for reevaluation (33 could not be contacted, 8 had undergone tonsillectomy and adenoidectomy, and 14 declined). Mean age was 6 +/- 4 (SD) years at the time of the initial study. The initial apnea index was 0.2 +/- 0.3, SpO2 nadir 95 +/- 2%, and peak end-tidal PCO2 was 47 +/- 3 mm Hg. At follow-up, all children were reported by their parents to still be snoring; in 20% snoring had reportedly increased, and in 70% there was no change. Eighty percent were thought to have difficulty breathing during sleep. For the group as a whole, there were no significant changes in apnea index, SpO2, or peak end-tidal PCO2. However, two children had mild OSAS on repeat polysomnography (apnea index of 3). We conclude that, in most children, primary snoring does not progress to OSAS over the course of several years. This study indicates that OSAS in the few individuals who do progress is mild. Parental concern about children's breathing patterns during sleep is a poor predictor of polysomnographic abnormalities. However, because many patients were lost to follow-up in this study, further prospective studies are needed.