The antihypertensive efficacy and acceptability of 3 doses of rilmenidine (0.5, 1 and 2 mg, once daily) and a placebo over a 4 week period have been compared in a randomised, double-blind, parallel-group trial in 60 mild to moderate hypertensive patients. Six patients dropped out: 4 in the 2 mg-group and one in the 1 mg-group because of adverse events, and one in the placebo group for personal reason. The blood pressure was significantly decreased after the 1 and 2 mg doses with the maximum antihypertensive effect already being obtained after 1 mg. A significant dose-effect relationship was shown for supine systolic blood pressure (P = 0.05) but not for the supine diastolic blood pressure. The most beneficial efficacy/acceptability ratio was achieved at the dose of 1 mg once daily, which demonstrated the maximum antihypertensive effect associated with a low incidence of adverse events.