Mitomycin C is an antibiotic used for its alkylizing effect in the treatment of broncogenic cancer. Haematologic, renal or pulmonary complications are sometimes severe. We report a case in a patient with poorly differentiated epidermoid bronchogenic carcinoma who developed clinical and radiological signs of bilateral infiltrating pneumonia due to mitomycine. This observation emphasizes the importance of bronchoalveolar lavage which implicated the immunological toxicity of mitomycine and explained the efficacity of corticosteroid treatment. Pulmonary lesions due to mitomycine were discussed.