Results of a study of the respiratory responses of 318 nonsmoking female workers to long-term tobacco dust exposure are reported. The mean total tobacco dust concentrations ranged from 0.9-27.5 mg/m3; the respirable fraction, from 0.3-3.6 mg/m3. The mean length of exposure to tobacco dust was 14.9 yr; 24% of the workers had been exposed to tobacco dust for 20 yr or more. Comparatively low prevalences of chronic respiratory symptoms were found, and only the prevalences of chest tightness and wheezing were significantly higher among workers exposed to tobacco dust than those of the control group (P < 0.01). Calculating the expected 1-s forced expiratory volume and forced vital capacity values by means of multiple linear regression equations, developed on the basis of data obtained in the 210 control subjects, revealed no significant differences between the measured and expected ventilatory capacity values among any of the groups of the workers observed. In contrast to negative findings with regard to chronic respiratory effects, significant acute decreases in ventilatory capacity during the work shift were recorded. No dose-response relationship was found between the level of exposure and the acute decreases in ventilatory capacity.