Objective To investigate the effect of lotensin taken in the morning or evening on the morning blood pressure in patients with hypertension.Methods 125 patients with hypertension were randomly divided into two groups. The patients in group A were treated by taking lotensin in the morning; the patients in group B were treated by taking lotensin in the evening. The 24-hour blood pressure was observed for both groups and the blood pressure before and after treatment as well as morning blood pressure were statistically analyzed . Results There was no significant difference in the total depressive effect and T/P of 24 hour mean blood pressure between two groups,howerer,there was a significant difference in the control of morning hypertension between group A and group B (P0.05).Conclusion For the control of morning hypertension, the best time of taking medicine is in the evening.