One hundred and forty school children, 75 boys and 65 girls, aged 7-18 years, underwent the following lung function tests: closing volume, slope of the alveolar plateau, maximal expiratory and inspiratory flows at 75, 50 and 25% of vital capacity, static and dynamic lung volumes. Lung volumes and maximal flows increase with height in an exponential way, the exponents varying between 2.6 and 3.1, while closing volume in per cent of vital capacity and the slope of the alveolar plateau decrease linearily with increasing height. Regression equations are given for each sex with height as determinant.