Long term effects on respiratory function have been found in adult professional divers and have indicated the development of small-airway disease. The aim of this report was to investigate pulmonary lung function and breathing pattern of recreational divers, especially in young subjects. Pulmonary function was measured in 84 air divers (aged 8 - 38 years) and in a matched control group of 89 subjects (aged 8 - 34 years). Static lung volumes, dynamic lung volumes and flows, transfer factor for carbon monoxide (T(Lco) ), maximal static pressures and CO(2) rebreathing test were measured. We observed no significant differences for all lung function parameters between divers and non divers in children and adolescents. Adult air divers showed a significant decrease in T(Lco) in absolute values (5.74 vs 6.26 ml x min(-1) x mmHg(-1) x l(-1), p = 0.03) and normal values and no significant difference in % predicted (112 vs 119 %), a higher maximal inspiratory pressure at functional residual capacity (-92 vs -74 cm H(2)O, p < 0.05) and at residual volume (-108 vs -88 cm H(2)O, p < 0.05) than adult controls. Adult divers also had a decreased resting respiratory frequency (13 c x min (-1) vs 17 c x min (-1) respectively, p < 0.01) and a higher carbon dioxide threshold (52 mm Hg vs 49 mm Hg respectively, p < 0.05) than adult controls. No significant differences occurred between adults divers and non divers for obstruction parameters. In this study, no airway obstruction or transfer factor reduction was observed in young recreational divers. Lower CO(2) threshold and higher inspiratory pressure were obtained in adult recreational divers compared to controls.