After inhaling a leather-impregnation spray in a confined space, coughing fits and dyspnoea occurred in a 40-year-old man and an 20-year-old woman, previously in good health. The cardinal symptoms on admission to an emergency ward were of interstitial pulmonary oedema in the X-ray but without increased pulmonary arterial pressure. Administration of corticosteroids both by aerosol and intravenously improved the acute symptoms within a few hours. Two subsequent chest X-rays demonstrated complete healing. The acute symptoms were caused by the impregnation spray producing an alveolitis or toxic lung oedema in both cases. The early topical administration of corticosteroids would appear to be the most important preventive and protective measure.