1. In previous studies a rat inhalation model was developed to investigate the efficacy of treatment in acute NO2 intoxication. 2. Desferrioxamine was administered intravenously to study its effect on histological alterations in lung tissue in rats after acute NO2 exposure. 3. Twenty four hours after exposure to 175 ppm NO2 for 10 minutes the lung injury observed by light microscopy in the desferrioxamine treated rats was less pronounced than in the saline treated rats. 4. Desferrioxamine appeared to provide more protection with a dose of 100 mg kg-1 24 h-1 than with 200 mg kg-1 24 h-1.