Nine oral airway replicas of children 6-14 years old were used for measuring deposition of 0.5-6.3 mu m diameter particles during inhalation of four representative (sinusoidal) breathing patterns typical of those observed during the use of nebulizers by children. For a given particle size and inhalation flow rate, deposition in the present child replicas is higher than in adults and is not well predicted by adult correlations, even when age-related scaling factors are applied. However, by using subject-specific geometrical dimensions of the airway replicas, dimensionless correlations that predict deposition of micrometer-sized particles in children's oral airways during tidal breathing are presented. Such best fitting correlation gives deposition efficiency eta(2) = [1-1/(4.99(stk Re-2.41(-0.17))+1)] x 100, where Re and Stk are Reynolds and Stokes numbers with length scale given by V/As where V is airway volume and A(s) is airway surface area. (C) 2012 Elsevier Ltd. All rights reserved.