Obstructive sleep apnea is a common disorder in childhood, particularly in the last decade when an increased prevalence of obesity has been documented. The neurocognitive and behavioral problems associated with this disorder have been known for a long time. However, the increased knowledge of cardiovascular and metabolic complications in adults with sleep apnea has been followed by a better understanding of the systemic effects of upper airway obstruction in children. Obstructive sleep apnea (OSA) has been shown to induce autonomic imbalance in children and to affect blood pressure, cerebral blood flow and cardiac function in an early phase. OSA may also induce chronic systemic inflammation and may contribute to the development of metabolic syndrome in obese children. Very recent research indicates that in children primary snoring, the mildest form of the sleep-disordered breathing spectrum, may also be associated with morbidity. It is, therefore, likely that these respiratory sleep disorders do not simply influence children's' performance in private and social life, but may more seriously affect children's' health. The aim of this review is to outline early systemic complications of obstructive sleep apnea and primary snoring in infants and children.