The antihypertensive effect and side reactions of perdipine was studied in 22 cases of essential hypertension using 20mg 3 times daily regimen for average period of 5 weeks. 1) Average reduction of 20mmHg in systolic and 17mmhg in diastolic pressure was observed and percentile reduction was 11.90% and 14.92%, respectively. The overall effect rate was 81.82%. The blood pressure lowered significantly after 2 weeks of treatment both in systolic and diastolic pressure. 2) There was no significant change in heart rates before and after treatment. 3) No specific side reaction was observed except 1 case in which discontinued the medication because of severe headache and fatigability on the 1st day of medication.