We have measured lung volumes, ventilatory flows, and the main thoracic dimensions in 65 Togolese adults aged between 25 and 55. We found that for Africans the total lung volume was 25% less and other lung volumes were 22% less than those for Caucasians. The difference in the total lung capacity was explained by smaller thoracic dimensions in Africans than in Caucasians of the same height; for the same TLC the residual volume was lower and the expiratory flows were higher in Africans than in Caucasians. The difference was most prominent on the proximal instantaneous flows giving a forced expiratory flow volume curve which was less straight and more concave at the end of expiration. Greater muscular strength, a larger diameter of the airways, and different alveolar development in the Africans may explain the differences.