Chronic renal failure (CRF) is often associated with hypertension, as a cause or a consequence. We studied the changes in blood pressure (BP), heart rate (HR), renal function (as measured by creatinine clearance), and plasma renin activity (PRA) in 19 hypertensive patients with CRF before, during and after oral administration once a day for at least 30 days of 5 mg tertatolol, a new beta-blocker. All patients were free of any antihypertensive medication for at least 1 month before administration of tertatolol. The dose of tertatolol given in this study was the same as that commonly used in patients with normal renal function. From day 0 to day 30 of tertatolol, measurements in the supine position were as follows: systolic BP (SBP) decreased from 168.4 +/- 4.6 to 145.3 +/- 4.3 mm Hg (p less than 0.01); diastolic BP (DBP) decreased from 106.1 +/- 2.4 to 87.1 +/- 2.0 mm Hg (p less than 0.01); HR decreased from 77.9 +/- 1.6 to 63.2 +/- 1.7 b.p.m. (p less than 0.01); PRA decreased from 1.816 +/- 0.521 to 1.052 +/- 0.323 ng/ml/h (p less than 0.01). Creatinine clearance remained stable: 37.1 +/- 4.1 versus 37.1 +/- 4.7 ml/min/1.73 m2 (not significant). Similar results (for SBP, DBP, HR and PRA) were obtained in the erect position. It is concluded that tertatolol in hypertensive patients with CRF: significantly lowers BP and HR without excessive bradycardia, significantly lowers PRA, the most important decrease being observed for the highest initial PRA, does not alter renal function, and has a good clinical acceptability.