Aims To investigate, in healthy volunteers, the relationships between the plasma concentrations (C, ng ml−1 ) of zabiciprilat, the active metabolite of the angiotensin I‐converting enzyme inhibitor (ACEI) zabicipril, and the effects (E) induced on plasma converting enzyme activity (PCEA, nmol ml−1 min−1 ), brachial and femoral artery flows (BAF, FAF, ml min−1 ), and brachial and femoral vascular resistances (BVR, FVR, mmHg.s ml−1 ) after a single oral administration of two doses (0.5 and 2.5 mg) of zabicipril.Methods The study was placebo‐controlled, randomized, double‐blind and crossover. E was related to C by the Hill model, E=Emax.Cγ/(CEγ50+Cγ ), fitted to the data of both doses simultaneously.Results We obtained (mean±s.d.) Emax=−99±1%, CE50=2.2±1.0 ng ml−1 and γ=1.0±0.4 for PCEA, Emax=55±26 ml min−1, CE50=5.1±4.0 ng ml−1 and γ=2.4±1.6 for BAF, and Emax=−45±10%, CE50=2.0±1.3 ng ml−1 and γ=2.3±1.4 for BVR. The parameters obtained for FAF and FVR were similar to those obtained for BAF and BVR, respectively. The CE95 (C required to induce 95% of Emax ) varies from 7 to 17 ng ml−1 for haemodynamic effects.Conclusions As zabiciprilat peak plasma concentrations average 20 ng ml−1 after the 2.5 mg dose of zabicipril, this dose of the drug should be sufficient to induce optimal haemodynamic effects.