ObjectiveTo compare 2.5 mg bendrofluazide daily (the standard antihypertensive dose), 1.25 mg bendrofluazide daily and 2.5 mg bendrofluazide on alternate days, in terms of reduction of blood pressure, patient compliance and adverse effect profile.DesignA single-blind parallel group trial of patients who were randomly assigned to 16 weeks' treatment with bendrofluazide at doses of 2.5 mg daily, 1.25 mg daily and 2.5 mg every other day after a 4-week placebo run-in period.SettingGeneral practices in the greater Belfast and Lisburn area in Northern Ireland.PatientsNinety-three patients with newly diagnosed or previously diagnosed hypertension, who had a mean diastolic blood pressure of 90–110 mmHg after receiving placebo for 4 weeks.Main outcome measuresReduction in blood pressure, patient compliance and changes in biochemical variables.ResultsSitting systolic and diastolic blood pressures in members of all three groups were significantly lowered with respect to baseline (P< 0.01) with no differences among groups. Overall mean compliance was 97%. No clear relation between dose and biochemical changes was apparent.ConclusionsBendrofluazide at doses of 1.25 mg daily or 2.5 mg every other day reduces blood pressure as effectively as does the conventional 2.5 mg daily regimen.