We compared the respiratory function of 19 pesticide factory workers and a control group of 43 other factory workers in Lebanon. The groups had no difference in smoking status. Baseline measurements of respiratory function showed significantly lower forced expiratory volume and flow rates (FEV1, FEF(25-75%), and FEV1/FVC ratio) among subjects working with pesticides, i.e. obstruction may be linked to chronic exposure to pesticides. After 4 hours of work, all respiratory variables were still significantly lower in pesticide-exposed subjects, but no acute changes in respiratory function were seen. Pesticide-exposed workers had 5.6 times higher risk of abnormal FEV1/FVC ratio and 16.5 higher risk for abnormal FEF(25-75%). Duration of occupation in the pesticide factory was significantly correlated with abnormal respiratory measures.