- Unlabelled: Obstructive sleep apnea syndrome (OSAS) has been reported among children aged 3-6 years. Adenotonsillar hypertrophy is the most common cause of OSAS. The upper airway obstruction results in repeated obstructive apneas and hypopneas, associated with oxygen desaturations and sleep fragmentation. OSAS in children is associated with higher respiratory morbidity as well as significant clinical consequences, mainly neurocognitive and behavioral problems, impaired growth and cardiac dysfunction. The objectives of the present study were to determine the clinical and sleep characteristics of OSAS in children younger than 2 years, and to evaluate morbidity and health care utilization of infants with OSAS. This retrospective study included 35 children younger than 2 years of age, referred for polysomnography because of suspected OSAS. The controL group included healthy children, matched by age, gender and pediatrician. Results: A total of 33 infants were diagnosed with OSAS. Mean apnea/hypopnea index [AHI) was 18.7 +/- 18.1 events/ hour [range 1.3-90.2]. In 10 infants a pattern of intermittent hypoxemia was observed. Infants with OSAS demonstrated a higher number of primary care clinic visits (20.8 +/- 14 vs. 12.1 +/- 6.6, P < 0.02). A higher percentage of children with OSAS visited the emergency room (60.6% vs. 32.2%, P < 0.03), and was hospitalized (36.3% vs. 12.9%, P < 0.03). Duration of hospitalization was also higher in the OSAS group [23.2 +/- 14.1% vs. 3 +/- 2.1%, P < 0.05). The number of drug prescriptions was higher among the study group [25.9 +/- 21.8% vs. 13.6 +/- 10.1, P < 0.03). Thirteen patients underwent adenoidectomy with or without tonsillectomy, resulting in improvement of AHI, decreasing from 26.4 +/- 24 before to 3.6 +/- 4.5 events per hour after surgery (p < 0.01). Conclusions: OSAS can be found in infants younger than 2 years of age. OSAS at this young age is characterized by a higher morbidity in comparison to healthy children. Early diagnosis and treatment may prevent morbidity in young children with OSAS.