OBJECTIVE This double blind, prospective, randomised, parallel group clinical trial was aimed at investigating the effects of nilvadipine or amlodipine in mild to moderate hypertensive patients over a 3-month treatment period. METHODS Eligible outpatients (supine DBP > or = 90 mmHg and < or = 110 mmHg and supine SBP < or = 180 mmHg) entered a maximum 15-day placebo run-in period and were randomised to receive once daily nilvadipine 8 mg or amlodipine 5 mg (to be doubled in the case of lack of response at day 30). Follow-up visits with measurement of supine and orthostatic blood pressure and heart rate were performed after 15, 30, 60 and 90 days of treatment. Standard laboratory tests and 12-lead ECG were performed at study entry and at the end of treatment; adverse events were collected at any time. RESULTS A total number of 168 patients, 83 in the nilvadipine and 85 in the amlodipine group, took part in the study: 15 and 14 in the two groups, respectively, were prematurely withdrawn. Supine DBP at endpoint similarly decreases in the two groups (-11.0 +/- 7.1 mmHg in the nilvadipine group and -12.7 +/- 8.2 mmHg in the amlodipine group), with no significant differences between groups at any time point. Measurements in the orthostatic position also did not show between-groups differences. Blood pressure was normalised in 61.8% of patients in the nilvadipine group and in 63.0% in the amlodipine group; responders to therapy were 64.5% and 69.1% in the two groups, respectively. Results of SBP also did not show differences between groups at any time point, except a more marked decrease in the amlodipine group compared to nilvadipine in the supine measurements at endpoint. A total number of 30 patients (36.6%) in the nilvadipine group and 23 (27.1%) in the amlodipine group reported adverse events (p = 0.24 between groups), which mainly consisted of vasodilatory effects (e.g. oedema, flushing and headache). A favourable lipid profile, i.e. a significant (p = 0.002 between groups) decrease of triglycerides levels and an increase of HDL-C, was observed in the nilvadipine group, compared with an increase of triglycerides in the amlodipine group. No effects on haematology, liver and renal function were observed in either group. CONCLUSIONS Nilvadipine or amlodipine produced comparable effects on DBP and shared a similar adverse effect profile. A favourable effect on lipid profile was observed following nilvadipine treatment.