This investigation was designed to study respiratory problems in farmworkers. To better define the consequences of this work environment on respiratory health, 814 farmworkers (738 male and 76 female) were studied. The mean age of the men in this study was 38 years, and the mean duration of their employment was 15 years. For women, the mean age was 44 years and the mean duration of their employment was 10 years. Of the men, 56.5% were regular smokers, and 23.7% of the women were regular smokers. A group of 635 control workers without significant exposure to air pollutants were matched by sex, age, employment, and smoking habit. The prevalence of chronic symptoms among male farmworkers was greater (P < 0.01) than among male control subjects for chronic cough (24.8% vs 11.4%), chronic phlegm (22.8% vs 9.1%), and chronic bronchitis (20.1% vs 7.4%). Among women farmworkers, a significant difference was noted with controls for chest tightness (farmworkers, 21.1%; control subjects, 0%; P < 0.001). There was a high prevalence of acute symptoms among male and female farmworkers. In particular, farmworkers complained of more frequent cough, eye irritation, dyspnea, and throat irritation than did control subjects. For respiratory symptoms in male and female farmworkers, odds ratios were generally significant for smoking, age, and duration of employment. Ventilatory capacity tests were significantly reduced for farmworkers compared with predicted values. Regression analysis of ventilatory capacity tests in male farmworkers as a percentage of predicted values demonstrated significant coefficients for employment and smoking. Our data suggest that farmworkers are exposed to noxious agents that cause respiratory symptoms and ventilatory capacity impairment.