Two hundred pigeon breeders from the county of Funen were invited to participate in the study. No definite cases of allergic alveolitis were found among the 68 participants. 40% had experienced airway and/or general symptoms in connection with pigeon exposure. However, most of these symptoms could be explained as irritation of the airway and chronic bronchitis. Precipitating antibodies to pigeon serum and to an aqueous pigeon bloom extract were determined. The antibody titers did not differ in pigeon breeders with or without symptoms. Smokers had lower antibody titers to pigeon antigens and a lower level of total serum IgG, but reported symptoms in connection with pigeon exposure as often as non smokers.