Cilazapril, a new angiotensin-converting enzyme (ACE) inhibitor, controls blood pressure (to 90 mm Hg or less) in patients with mild-to-moderate hypertension within 2–3 weeks of initiating treatment (2.5–5.0 mg once daily); this effect was maintained in long-term observations over 1 year. Hemodynamic investigations demonstrated that the antihypertensive action of cilazapril is induced mainly by a decrease of peripheral vascular resistance accompanied by a decrease of pulmonary capillary wedge pressure. Furthermore, cilazapril decreased left ventricular mass index in essential hypertensive patients within 6 months of therapy at doses of 2.5–5.0 mg once daily, thus reversing left ventricular hypertrophy induced by hypertension. In other studies cilazapril was shown to ameliorate glucose tolerance and insulin sensitivity in nondiabetic hypertensive patients, and in hypertensive diabetic patients improvement of renal function was observed. Incidence and severity of side effects caused by cilazapril were comparable to those seen by other ACE inhibitors. Although experimental data provide evidence for vascular, antiatherosclerotic protection by cilazapril, these effects must be proven by long-term prospective studies in humans.