Hypertension is a major risk factor for stroke and heart disease in the elderly. Eighty-one hypertensive subjects with mild cognitive impairement, aged over 70 years, were drawn from a community screening programme and randomized to either 12.5 mg captopril twice daily or 2.5 mg bendrofluazide daily in a double-blind trial. Subjects were excluded if they had previously received antihypertensive treatment. The mean blood pressure was reduced from 193/101 mmHg to 154/87 mmHg by captopril and from 188/102 mmHg to 151/89 mmHg by bendrofluazide after 24 weeks; there was no significant difference between the two drugs. Seven subjects withdrew due to adverse events. Adverse events occurred more frequently during the 2-week placebo phase than during active treatment with either drug. The only significant detrimental changes in pre-existing conditions were in 3 subjects (2 captopril, 1 bendrofluazide) who were noted to have worsening of their cataracts. One subject on captopril and 4 subjects on bendrofluazide became hypokalaemic. The trial results support the use of captopril as an alternative to bendrofluazide as a first-line antihypertensive agent in the community for elderly people, but large studies are required to measure accurately effects on significant morbidity and mortality.