In a prospective randomised cross-over study, we compared the effects of ACE inhibitor temocapril and calcium channel blocker (CCB) amlodipine on ambulatory blood pressure in 59 asymptomatic elderly hypertensive patients (mean age 69 years). This study was performed in a cross-over fashion after a 2-week placebo period and 4 to 8 weeks each of treatment with temocapril and amlodipine. Of those 59 hypertensive patients, three patients with side effects and 10 patients whose office BPs did not achieve the target BPs were excluded, and the remaining 46 were analysed in this study: they consisted of 30 dippers, with a night time reduction in systolic BP (SBP) > or = 10% and 16 non-dippers, with reduction by < 10%. At the baseline, there were no significant differences in the office, 24-h or daytime BPs between the two groups (dippers and non-dippers). Though the office BPs and daytime BPs were successfully controlled to the same levels with both treatments and in both dipping groups, the antihypertensive effects were stronger with the CCB than with the ACE inhibitor in the night time and morning, especially in non-dippers. We conclude that even though office BPs were controlled successfully to almost the same levels, there is a possibility that these long-acting drugs have differential antihypertensive effects on night time and morning BPs among hypertensive patients with different night time BP dipping statuses.