We report on an acute accidental inhalation of sulfurous anhydride, by a man aged thirty in the course of his work. This intoxication, followed by acute respiratory distress, first showed an improvement, then re-aggravation 26 days after the accident. This episode has not been explained. The patient then developed a chronic obstructive bronchopathy. Ten years of regular observation allows us to maintain that the severe obstructive syndrome which the patient presents has never regressed (FEV1/FVC = 32%), and must be associated with a chronic toxic obstructive bronchopneumopathy.