In a cohort of 136 hypertensive patients started consecutively on enalapril the incidence of persistent dry cough by life-table analysis was 14.6% (95% CI 10.2-19.0%). The incidence in women (19.2%; 95% CI 11.3-27.1%) was twice that in men (9.7%; 95% CI 6.6-12.8%). Dry cough was unrelated to age, smoking habit, renal function, or the dose and duration of enalapril treatment. In one half of patients who developed cough enalapril had to be stopped. The incidence of withdrawal due to cough was 6.0% (95% CI 4.5-7.5%), and cough was by far the most common reason for discontinuing enalapril treatment. Reviewing previous studies of enalapril-induced cough, it is evident that postmarketing surveillance studies have grossly underestimated the incidence and importance of this side-effect. Surveys in hospital clinics have slightly underestimated the true incidence through failure to use life-table methods of analysis.