We present the first reported case of hypersensitivity pneumonitis (HP) due to Aspergillus glaucus in a mushroom worker. The Aspergillus glaucus group is one of the most popular storage fungi and a possible subsidiary etiologic agent of farmer's lung, but no case of hypersensitivity pneumonitis (HP) due to A. glaucus has been reported. This first case may demonstrate the etiologic role of A. glaucus in HP and in farmer's lung.