Children are not small adults, and this fact is particularly true when we consider the respiratory tract. The anatomic peculiarities of the upper airway make infants preferential nasal breather between 2 and 6 months of life. The paediatric larynx has a more complex shape than previously believed, with the narrowest point located anatomically at the subglottic level and functionally at the cricoid cartilage. Alveolarization of the distal airways starts conventionally at 36-37 weeks, but occurs mainly after birth, continuing until adolescence. The paediatric chest wall has unique features that are particularly pronounced in infants. Neonates, infants and toddlers have a higher metabolic rate, and consequently, their oxygen consumption at rest is more than double that of adults. The main anatomical and functional differences between paediatric and adult airways contribute to understanding of various respiratory symptoms and disease conditions in childhood. Knowing the peculiarities of paediatric airways is helpful in the prevention, management and treatment of acute and chronic diseases of the respiratory tract. Developmental modifications in the structure of the respiratory tract, in addition to immunological and neurological maturation, should be taken into consideration during childhood.