Pulmonary function (PF) tests are procedures that measure the function of the lungs, revealing problems in breathing, and therefore are highly important in diving. In this article, we studied the PF in military divers and defined the differences between (A) males (n = 32) and females (n = 27), (B) male smokers and nonsmokers, and (C) female smokers and non-smokers. PF was established by measuring: the large airway variables: inspiratory-vital capacity, forced-vital capacity, 1-second forced-expiratory volume, and 1-second forced-expiratory volume:forced-vital capacity ratio; and small airway variables: peak-expiratory flow, maximal-mid-expiratory flow, and maximal-expiratory flow after 50% and 75% of exhalation, all in absolute and relative (predicted for age and stature) values. The t test showed a significant (p < or = 0.05) difference between smokers and nonsmokers, but only in the relative inspiratory-vital capacity. A multivariate analysis of the variance revealed significant differences between smokers and nonsmokers in large airway variables for males and females. The possible explanations regarding the metrics, the variable relationships, and the influence of physical fitness training are discussed.