The treatment of the pulmonary toxicity induced by carmustine is nowadays based on the use of corticosteroids that generally lead to a rapid resolution of pneumonitis. On the contrary, no therapeutic alternatives are reported for those patients who do not respond to steroids. We describe a case of non-Hodgkin's lymphoma in a patient who developed a severe interstitial pneumonitis after an autologous transplantation including carmustine in the conditioning regimen. He was successfully treated with an association of steroids and cyclosporine A with a rapid improvement of symptoms and a complete resolution of pneumonitis. This is, to our knowledge, the first case of carmustine-induced pneumonitis, resistant to steroids alone, successfully treated with cyclosporine A. This suggests an immunoallergic mechanism in the pathogenesis of the damage, which can be reversed with prompt therapy.