The author does a general survey on this subject. Having evoked the EAA history, he describes the clinical syndrome with 3 forms (sharp to chronic). He relates in a first part, the main forms linked with rural occupation, from farmer's lung disease, the most frequent, to illnesses dues to cereals, woods exposition, then the one in touch with industry as coffee workers disease, and breeders of silkworms. At last, the ones in connection with urban activities as air-conditioner disease. These descriptions ended with EAA caused by a drug. Having evoked the complementary investigations necessary for diagnosis, he insists on the alveolitis washing and biochemicals studies. In conclusion, the author insists on the interest of steroids treatment in attacks.