SummaryAfter a latent period of 3 weeks following an intense inhalational exposure to mouldy corn, a farmer developed pneumonilis apparently of a hypersensilivity pneumonitis type. This illness was associated with serum precipitating antibodies against antigens in the mouldy corn and against antigens ofAspergillus flavusandfumigatus. The former organism was cultured from the mouldy corn and precipilin bands of identity between an extract of mouldy corn and aspergitlus antigen were demonstrated using the patient's serum. Organizing bronchiolilis oblilerans was found in pulmonary tissue after death occurred, the latter presumably due to pulmonary embolism. This case is believed to represent the occurrence of hypersensitivity pneumonitis following massive inhalation of the spores of the genusA. flavuspossibly with transient respiratory infection with these organisms but without systemic invasion of the host.