BACKGROUND: The hypotensive effect of the lisinopril, a long acting angiotensin converting enzyme inhibitor, was studied. METHOD: 10mg of lisinopril was administered in 30 hypertensive Korean adults during twelve week after a weeks observation for washout with stepwise increments of the dose according to the patients blood pressure in every two weeks. RESULTS: The supine blood pressures were decreased from 173.3+/-27.9/105.7+/-19.4mmHg to 131.8+/-23.1mmHg/81.4+/-18.7mmHg at the end of twelve weeks durg therapy(P<0.05). The standing blood pressures were also decreased conferrably and to the some lower levels. Hematologic examination and blood chemistry revealed no discernible abnormal findings before and after the treatment. During the period of the study a few probably drug-related symptom such as dry cough and dry mouth developed but not troublesome enough to stop administering. CONCLUSION: Lisinopril 10mg once daily regimen is well tolerated and effective in the treatment of hypertensive patients.