Regarding 5 recent cases of cough induced by inhibitors of angiotensin conversion enzyme (CEI), the authors emphasize the still underestimated frequency of this annoying and sometimes disabling side-effect (10 to 15% of cases). They remind of their clinical and evolutive characteristics: dry cough, predominantly at night, often occurring rapidly, sometimes delayed (up to 17 months) after introduction of the CEI and unrelated to the dosage. The cough usually disappears in two to three days (up to 8 days) upon discontinuation of the treatment. The test of discontinuation-reintroduction, possibly crossed (captopril/enalapril) is used in questionable cases as a diagnostic test. Besides, this diagnosis must be made rapidly in order to avoid costly, unnecessary laboratory tests which are sometimes unpleasant for the patient. The cough could be explained by an irritation of the bronchial mucosa secondary to bradykinin and pulmonary E2 prostaglandins elevation, under CEI.