Objective To observe effect of reducing blood pressure with enalapril in 30 mild-morderate hypertensives by ambulatory blood pressure monitoring(ABPM). Methods The ambulatory blood pressures( ABP) were measured by ABPM before and after 4-weeks single-blind treatment. 10-15mg enalapril was administrated once daily at early morning. Results Enalapril administrated 4-week could reduce BP smoothly and efficiently throughout 24-hour in hypertensives (P<0.05)

and slightly blunt circadian BP rhythm. Conclusion Enalapril administrated once daily at early morning in hypertensives which night blood pressure is normal or slightly high should be suitable. with both day and night high blood pressure and after treatment night BP reduction unsatisfactory

another dose of enalapril may be administrated at night.