The hypotensive effects of acebutolol and bendrofluazide were studied comparatively, used alone or in association, using a permutation method over three consecutive six week periods, in 47 patients aged over 21 whose diastolic pressure prior to treatment was in excess of 100 mm Hg. Whether used alone or associated, the drugs were prescribed at the following daily doses: acebutolol 500 mg, bendrofluazide 5-15 mg. After six weeks and at the end of the trials (18 weeks), acebutolol proved to have an hypotensive effect, less marked when given alone than in association. It provided significant relief from anxiety, especially when prescribed alone during the latter part of the test. Side effects were unfrequent on the whole and without marked predominance for any type of treatment.