The 24-h profile of blood pressure (BP) was studied in 28 patients (21 males and 7 females) with congenital heart failure (CHF) of NYHA class II-III (ejection fraction <45%). The patients were 46 to 76 years of age and had postinfarction cardiosclerosis. They had not received ACE inhibitors before. Two groups were formed basing on the presence of hypertension. Perindopril was administered in a single daily dose of 2 mg or higher if demanded to reduce symptoms of CHF and/or to normalize BP. The treatment continued for 3 months. The 24-h BP profile was assessed using portable device SpaceLabs 90207 (USA). In CHF patients with hypertension perindopril significantly lowered mean 24-h, day and night BP and its loads, reestablished two-phase circadian rhythm of AP and corrected BP variability. In CHF patients free of hypertension significant changes of the profile were not registered. It is evident that unwanted changes in the BP 24-h profile due to perindopril were absent in CHF normotensives.