For two weeks, with the exception of one case involving long-term therapy, 15 hypertensive patients received 100 mg of dilevalol once daily and seven patients received 50 mg. Blood pressure and heart rate were measured and digital pulse plethysmography (DPG) was performed before and after the two-week trial. Systolic and diastolic blood pressure decreased significantly during treatment; heart rate did not change. There were also significant changes on the three DPG measures of vasodilatation: peak amplitude increased, the dicrotic index decreased, and peak amplitude on the differentiated DPG increased. A weak correlation was found between the changes in systolic blood pressure and changes in the two measures of DPG peak amplitude. It is concluded that dilevalol is effective in the treatment of hypertension and that DPG is a sensitive noninvasive method to measure vasodilatation.