OBJECTIVE:The aim of this study was to compare the antihypertensive efficacy and tolerability of the calcium channel antagonist amlodipine besylate versus the angiotensin II type 1 receptor antagonist candesartan cilexetil in hypertensive patients. PATIENTS AND METHODS:After a 2-week placebo washout period, 326 patients with essential hypertension were randomised to receive amlodipine 5mg once daily or candesartan cilexetil 8mg once daily in a double-blind, parallel-group design with a 12-week active treatment period followed by a 4-day placebo drug-free period. The initial daily dose could be doubled at week 6 if office diastolic blood pressure (DBP) was still >/=90mm Hg. BP changes were assessed daily through patient self-measurements, and fortnightly by office BP measurements. RESULTS:A total of 294 patients (151 amlodipine and 143 candesartan cilexetil) were included in the per-protocol analysis of the primary endpoint of BP change from baseline at 12 weeks. Reductions in sitting office systolic BP (SBP) [amlodipine 24.4mm Hg, candesartan cilexetil 22.3mm Hg] and DBP (amlodipine 14.9mm Hg, candesartan cilexetil 14.8mm Hg) were statistically equivalent within the chosen range of equivalence (5mm Hg for SBP and 3mm Hg for DBP). The proportion of controlled patients (office BP <140/90mm Hg) at the end of therapy was similar in both treatment groups (amlodipine 46.9%, candesartan cilexetil 44.4%). The reduction in self-measured DBP was significantly greater (p < 0.05) for amlodipine (7.2mm Hg) compared with candesartan cilexetil (4.8mm Hg). There was no significant difference between the two treatments in the incidence of adverse events reported. CONCLUSIONS:Amlodipine besylate and candesartan cilexetil were both very effective in lowering office BP after 12 weeks of treatment. There was a trend towards a better self-measured BP reduction with amlodipine compared with candesartan cilexetil. The overall incidence of adverse events was comparable between the two treatments.