The respiratory toxicity of vinca alkaloids only appears when they are associated with mitomycin. Few reports have been noted with vinorelbine, the last molecule of this class. We report 4 cases of acute dyspnea induced by the association mitomycin-vinorelbin, The 4 patients were treated for lung cancer. At the end of the injection of vinorelbin appeared an acute bronchospasm. In 3 cases, the symptoms disappeared with broncho-dilatators and corticoids. The fourth patient needed an additional respiratory support. After the acute syndrome, a chronic respiratory insufficiency developed in three patients. Two patients required continuous oxygenotherapy. The pulmonary toxicity of the mitomyin-vinca alkaloids association is characterized by an acute dyspnea. The dyspnea appears within 2 hours after the end of the administration of vinorelbine. The frequent existence of airflow obstruction in patients with lung cancer exposes to high risk of severes incidents. These treatments must be stopped at onset of the first pulmonary symptom. The association of mitomycin with vinorelbine (as for all vinca alkaloids) in chemotherapy protocols for treatment of non-small-cell lung cancer should not be indicated because there is an increase of the toxicity without increase of efficiency.