Since coronary artery and cerebrovascular diseases are the most common serious complications of long standing hypertension, there is a great potential for combining treatment with aspirin and angiotensin-converting enzyme inhibitors (ACE-I). However, the data regarding interaction of aspirin and ACE-I in relation to blood pressure control and survival benefits are controversial and inconclusive. We presumed that the appearance of dry cough in some of the patients following initiation of ACE-I treatment could be used as a marker for the presence of their influence, whereas ACE-I cough attenuation after addition of aspirin to treatment could be a sign of aspirin and ACE-I interaction on clinical level. The present study was aimed to use ACE-I induced cough as a clinical marker of ACE-I activity to determine whether dose-dependent aspirin and ACE-I interaction does exist. In a cohort of 750 consecutive ACE-I treated hypertensive and postinfarction outpatients we identified 78 (10.4%) non-smoking ACE-I related coughers. Out of them, 31 (21 men, 10 women; mean age 61 ± 0.9 years) agreed to take part in the study, which was aimed to compare two regimens of combined ACE-I and aspirin treatment (self-matched control data): intermediate (500 mg daily) vs low-dose aspirin (100 mg daily). On each visit the life quality, cough severity (CS, 0-4) and frequency (CF, 0-10) scores were registered. Low doses