Background: Enalapril is an angiotensin-converting enzyme inhibitor that has been widely used in treating hypertension, congestive heart failure, DM and various renal diseases. Cough has been recognized as a side effect of angiotensin-converting enzyme inhibitors. Therefore we studied the incidence and the chracteritics of Enalapril induced cough in Korea. Method: The sixty eight patients with Enalapril who visited out-patients department of internal medicine, Han-Il General Hospital during the period from april 1992 to october 1992 were included in this study. In all patients careful history taking and review of chart was done. Patients with respiratory disease were excluded. The criteria of angiotensin converting enzyme inhibitor induced cough was that cough developed after administration of Enalapril and improved after discontinuing drug and readministration of drug induce resume of symptom. Resnlts: Subjects include 34 males, 34 females and their average age was 53.3 years, Diseases of theirs were hypertension (57 cases}, congestive heart failure (5 eases), various renal disease (28 cases) and 9 patients of them were smokers. Average drug dosage was 11.7 mg a day and average administration duration was 182 days. Of the 68 patients, 23 patients (33.8%) had chronic cough due to enalapril, which had 12 male and 11 female patients. The cough disappearing time after withdrawal of the angiotensin-converting enzyme inhibitors was average 7.8 days. In 16 patients (two thirds of them), cough disappeared within 4 days after drug withdrawal. 9 patients had to stop taking drug because of severe cough. Generally the characters of cough induced by angiotensin-converting enzyme inhibitors were dry, persistent, tickling and tended to develope especially at night, Conclusion: Cough is not uncommon side effect in angiotensin-converting enzyme inhibitor users. There fore clinician should consider angiotensin-converting enzyme inhibitor induced cough initially when cough developed after angiotensin-converting enzyme inhibitor administration.