A cross sectional study of respiratory symptoms and pulmonary function in poultry workers was conducted. The participants were 252 men and 91 women employed at poultry farms in Croatia, average age 37 years. The poultry workers were employed as growers and catchers in confinement buildings. Controls were nonexposed workers employed in packing food products. Poultry workers reported more symptoms of chronic cough, phlegm, bronchitis, and chest tightness than controls. Symptoms were higher in poultry workers who also smoked. Those who worked more than 10 years had significantly more symptoms than those who worked less than 10 years. Significantly lower ventilatory capacity data, compared with expected, were obtained for forced vital capacity (men, 80.6%; women, 82.8%) and forced expiratory volume (men, 88.9%; women 94.6%). Extracts of poultry dust from the farms tested on isolated male Hartley-guinea- pig trachea were studied for contractile response. A dose response relationship between poultry extract and contractile response occurred. Pretreatment with certain drugs, including pyrilamine, LY171883, and indomethacin, significantly reduced the contractile activity of the poultry extract. The authors conclude that airway constricting agents exist in the dust of poultry workplaces, and environmental monitoring is necessary to insure safety.