SummaryA typical case of pulmonary eosinophilic granuloma, ascertained by lung biopsy, is reported. Immunological studies showed multiple hypersensitivity against wood dust extracts, horse serum, horse hair and danders proteins. Inhalation of these two groups of substances reproduced most of the acute symptoms of the disease. Therefore, a causal relationship seemed highly probable.To our knowledge, this is the first case of pulmonary eosinophilic granuloma in which an allergic origin could be substantiated.