The present investigation was designed to the study of respiratory symptoms and immunologic changes in workers of a poultry farm, chronically exposed to various organic allergens (avian, fungi, etc.). The group studied included 202 exposed subjects (109 at the slaughter house, 93 on the farms) and 100 controls. Although the group was chiefly made up of young women, non-smokers, exposure to avian allergens increased the prevalence of respiratory symptoms. Thus, coughing and expectoration was noted in 8.2% of the workers in the slaughter house and 10.7% of those on the farms, wheezing being present especially in the latter (13.9%). An apparently obstructive pulmonary function was observed in 16.10% of the farm hands and 1% of controls. The study of humoral immunity suggested that the presence of precipitation antibodies (76% positive reactions in the farms, 63% in the slaughter house, 44% among the controls) indicated exposure to avian allergens rather than the clinical and radiologic presence of the disease.