The aims of this paper are: to examine the physiological rationale for noninvasive respiratory support (NRS) in children with acute respiratory failure (ARF); to review clinical available data and to give some practical recommendations to its safe application. NRS is the delivery of ventilatory support without the need of an invasive airway. Two types of NRS are commonly used in the pediatric population: non-invasive continuous positive airway pressure (nCPAP) and non-invasive positive pressure ventilation (nPPV). In general, the evidence to promote the use of NRS in children with ARF is scarce. However, two randomized studies have been recently published suggesting that nPPV ameliorates clinical signs and gas exchange while reducing the need for endotracheal intubation. Moreover, nCPAP and heliox may improve clinical scores and CO2 washout in infants with severe bronchiolitis, without major complications. Data from non controlled studies show that NRS unloads the respiratory muscles and that the helmet can be a valid alternative to facial and/or nasal mask when nCPAP is administered to children in the early stage of ARF.