Data on the safety, tolerability and efficacy of the new angiotensin-converting enzyme (ACE) inhibitor cilazapril were obtained in a multicenter observational study carried out in a general practice setting. A total of 33,841 hypertensive patients were prescribed cilazapril 2.5-5.0 mg per day and followed for an average of 109 days. 28,792 patients (85.1%) had a baseline diastolic blood pressure (BP) > or = 95 mm Hg. 24,649 patients received cilazapril alone. during the observation period the mean blood pressure of these patients fell from 177/105 to 148/87 mm Hg (an average drop delta of 29/18 mm Hg). The response rate (diastolic BP < or = 90 mm Hg and delta > or = 10 mm Hg) in these patients was 78.9%. Adverse events were reported by 7.3% of all patients. In all, 3.7% of patients discontinued cilazapril treatment because of side effects. The most frequently reported side effect (1.5% of cases) was the dry cough typical of ACE inhibitors. The doctors judged the efficacy of cilazapril as very good or good in 89.8% of cases and its tolerability as very good or good in 94.6%. This reflects the good compliance (regular tablet intake) of more than 90% of patients.