The effects of a mid-term antihypertensive treatment with Acebutolol (A) 400 mg once-daily alone, Enalapril (E) 20 mg once-daily alone and their combination (A + E) in 12 hypertensive patients (pts.) have been evaluated. The diastolic (DBP) and systolic (SBP) blood pressure values have been evaluated in supine and upright position and at the end of an exercise test. Basic values obtained after 3 weeks of treatment with placebo have been matched with values observed after 3 months of each treatment (A; A + E; E). In order to evaluate the effectiveness of the combination, pts. were divided into two groups: the first group was given A, than A + E and finally E; in the second group the order was reversed. Our findings showed a more significant reduction of DBP in supine and upright position and after exercise (p less than .05) and of SBP in supine and upright position (p less than .05) after treatment with E. The addition of A to E did not produce a further significant reduction in blood pressure values except after exercise (p less than .01).