The prevalence of respiratory symptoms was registered and ventilatory function was determined in 164 men exposed to oil mist. The average exposure time was 16.2 yr. Office workers (159) served as controls. The exposed men reported more respiratory symptoms; 14% of the exposed nonsmokers vs. 2% of the nonsmoking controls having cough at least 3 mo./yr. There were no significant differences between spirometric measurements and chest roentgenograms of the men exposed to oil mist and those of the office workers. The lung function of 25 nonsmoking exposed men was examined with other lung function tests. The mean values for closing volume, slope of the alveolar plateau, total lung capacity, residual volume, elastic recoil at various lung volumes and diffusion capacity did not differ significantly.