The three angiotensin converting enzyme (ACE) inhibitors cilazapril, perindopril and CGS 14824A were administered for 8 days to, respectively, 6, 5 and 5 normotensive healthy volunteers maintained on an unrestricted salt intake. Before starting treatment, as well as on the last day of therapy, an ambulatory blood pressure profile was obtained with a semi-automatic blood pressure recorder (Remler M2000). An additional blood pressure recording was performed 1 month after the end of the 8-day course of treatment with cilazapril and CGS 14824A. Eight day ACE inhibition with any of the 3 drugs did not result in a consistent decrease of ambulatory blood pressure recordings. This suggests that in normotensive subjects on a free salt intake the renin-angiotensin system may not be a key determinant of blood pressure.