Thirty-two hypertensive patients (mean age 52.9 +/- 1.7 years) with a supine diastolic blood pressure (DBP) between 95 and 130 mm Hg (mean 104.3 +/- 0.8) received, following a randomized allocation, either tertatolol 5 mg (n = 16) or acebutolol 400 mg (n = 16) in a single daily dose. The 2 drugs were administered during a 3-month treatment period (from day 0 to day 90) in a single-blind fashion. At rest (n = 32), the decrease of supine systolic blood pressure (SBP) reached 27.3 mm Hg after 1 month of tertatolol treatment (from day 0 to day 30; p less than 0.01); there was a further decrease of 5.1 mm Hg from day 30 (D30) to day 90 (D90) (NS). The corresponding decreases after acebutolol treatment reached respectively 22.3 mm Hg (p less than 0.01) and 5.7 mm Hg (p less than 0.05). Similar results were observed in the upright position. The decrease of supine DBP reached 14.0 mm Hg in patients treated with tertatolol from D0 to D30 (p less than 0.01); a further decrease of 2.9 mm Hg occurred from D30 to D90 (NS). The corresponding decreases in patients administered acebutolol reached respectively 7.6 mm Hg (p less than 0.01) and 5.2 mm Hg (p less than 0.01). Similar results were observed in the upright position. On submaximal exercise (ergometric bicycle; n = 18), the decrease of SBP reached respectively 31.3 mm Hg during tertatolol treatment from D0 to D30 (p less than 0.01) and 8.8 mm Hg from D30 to D90 (NS).(ABSTRACT TRUNCATED AT 250 WORDS)