The antihypertensive effect and side reactions of perdipine were evaluated in 30 patients with essential hypertension. The results were as follows; 1) Before medication and after 2, 4, 5 and 8 weeks of medication, the over all average systolic and diastolic blood pressure were 170+/-13/104+/-7, 152+/-13/93+/-6, 146+/-11/91+/-6, 143+/-9/90+/-7, and 141+/-10/89+/-7mmHg, respectively. In 89% of all cases, marked or moderate degree of antihypertensive effect was observed. 2) There were no significant changes in heart rates before and after treatment. 3) In 83% of all cases, improvement of symptoms were observed. 4) The side reactions of oral perdipine were mild constipation, anorexia, facial flushing, dizziness, and headache, respectively one case. but there were no side reactions which required discontinuing the treatment, except 1 case which discontinued the medication because of severe bradycardia and dizziness.