In a double-blind parallel study, 20 elderly hypertensive subjects (mean age 85 years) were treated either by nicardipine or by nifedipine in slow-release form for 7 days. Blood pressure was measured by ambulatory, non-invasive daytime monitoring. Efficacy of both drugs was similar on the seventh day of treatment. However, the hypotensive effect induced by nifedipine was maximal on the first day of treatment, in contrast to the progressive effect induced by nicardipine. In 2 cases, marked hypotension was observed after the first tablet of nifedipine.