Acebutolol, a new cardioselective beta-adrenoceptor antagonist, has been studied in 40 hypertensive patients (pts.) for a period of 6 months, 25 patients (group A) had never taken any antihypertensive agent, 15 pts. (group B) were previously treated with antihypertensives. This two groups are statistically different for the age (39.8 y. group A; 49.6 y. group B) for the values of basal blood pressure (BP) (175/105 mmHg group A; 197/114 mmHg group B) and for disease duration (9.9 months group A; 39.0 months group B). A significant antihypertensive response was obtained already at the 15th therapy day for the two groups, treated with acebutolol. Further, a little reduction of BP was obtained at the 3rd month going on with therapy; then the BP values showed non significant variation till the end of the study. Orthostatic hypotension were not remarked. After 3 months, acebutolol treatment 41% pts. rised diastolic BP (DBP) below 90 mmHg and 35% pts. had a DBP between 90 and 100 mmHg. The average values of heart rate have been significantly reduced after 15 days of therapy with sligh variations during the following month. The optimal mean daily dosages of the drug were obtained with titration in three months (540 mg/day group A and 740 mg/day group B). Regarding side effects rised during therapy, one patient showed "paradox hypertension" and another bradycardia which justified the interruption of the treatment. In our opinion, on the basis of the results obtained acebutolol shows a good efficacy in the treatment of hypertension and a very high tollerability.