[Hypersensitivity pneumonitis].

Hypersensitivity pneumonitis (HP) is an interstitial lung disease associated with repeated exposure to a wide range of inhaled organic dusts and related occupational allergens. Immunological phenomena have been reported to play an essential role in initiating and maintaining the disease. Natural history, clinical findings, chest radiography, pulmonary function, immunological investigations, the use of the bronchoalveolar lavage, the prognostic and management of HP are discussed.