Hypersensitivity pneumonitis in a mouldy house

Two cases of hypersensitivity pneumonitis, one confirmed by histopatholgy, are described. The patients were members of different families and developed the disease as occupants, at separate times, of the same inner-city dwelling. We believe the disorder resulted from exposure to thermophilic microorganisms prevalent in their domestic environment. Both patients recovered after moving from this place of residence. The need for greater awareness of this variety of hypersensitivity pneumonitis is stressed.