Essential hypertension is an important public health problem in Korea-being common, asymptomatic, easily treatable, and often leading to lethal complication in left untreated. The number of patients with hypertension has been significantly increased, and this factor may be an importnat one responsible for the increase in cardivascular mortality during past 20 years in Korea. As the drug therapy for hypertension needs longer period, it is very important to evaluate the efficacy and the adverse effects. Thirty patients(17 men and 13 womon) with essential hypertension were evaluated in this study. All patients had received oral Isradipine 1.25~2.5mg b.i.d. for 8 weeks. 1) The systolic and diastolic pressure were decreased significantly(166.8+/-9.0mmHg vs 147.3+/-12.0mmHg, p<0.001 and 100.3+/-4.0mmHg vs 90.3+/-6.1mmHg, p<0.001, respectively) 2) Heart rate, body weight, laboratory tests, chest X-ray, ECG studies were not changed significantly. 3) The systolic pressure was lowered by 20mmHg or more in 17 cases(56.7% of total), and the diastolic pressure was lowered by 10mmHg or more in 20 cases(66.7% of total) at 8 weeks after Isradipine administration. 4) The adverse effects of Isradipine were edema in 3(10%), constipation in 2(6.7%), headache in 2(6.7%), and insomnia, dizziness and dry mouth in 1 patient respectively, and none of them discontinued Isradipine administration due to adverse effects. In many patients with essential hypertension there is an effective response to Isradipine, even though there may be some mild adverse effects.