The efficacy and safety of cilazapril in chronic heart failure have been extensively investigated in an international clinical program in patients with underlying chronic heart failure with ischemic heart disease or dilated cardiomyopathy. Cilazapril in single doses of 1.25–5 mg produced a significant dose-dependent reduction in pulmonary capillary wedge pressure and systemic vascular resistance and a significant increase in cardiac index. In placebo-controlled studies, 1–5 mg of cilazapril once daily for 12 weeks prolonged predose exercise test duration and improved New York Heart Association classification status and signs and symptoms of chronic heart failure, including paroxysmal nocturnal dyspnea. Up to 86% of patients receiving these dosages had improvement, with only 12% of patients requiring the higher dose, 5 mg. These data indicate that cilazapril is effective when administered once daily to patients with chronic heart failure receiving concomitant therapy with digitalis and/or a diuretic. The safety of cilazapril in patients with chronic heart failure has been evaluated in 1,163 patients administered from 0.5 to 15 mg once daily for treatment periods ranging from I day to 57 months. Cilazapril was administered to 500 patients for at least 6 months, 264 patients for at least 1 year, and 101 patients for at least 2 years. The most frequently occurring adverse events were dizziness, coughing, dyspnea, fatigue, angina pectoris, and headache. Cilazapril was equally well tolerated by young and elderly patients. Treatment was discontinued due to adverse events in 12.9% of patients, mainly as a result of coughing (1.7%) and dizziness (1%). Forty-four patients (3.8%) died during cilazapril therapy or during a period without treatment. Of these deaths, 93% were due to cardiac causes, especially rhythm disturbances. Changes in laboratory parameters were minor and rarely resulted in withdrawal of treatment. There was no symptomatic hypotension in patients after a first administration of 0.5 mg of cilazapril. The data demonstrate that cilazapril is an effective and safe therapy in patients with chronic heart failure. Cilazapril therapy should be initiated at 0.5 mg and titrated to 1–2.5 mg once daily and up to 5 mg when necessary.