Objective To compare the antihypertensive efficacy and the cough occurrence of imidapril versus benazepril on mild-to-moderate essential hypertension. Methods A randomized, double-blind, double-mimic controlled trial was performed. Patients with essential hypertension (blood pressure was considered eligible after treatment with placebo for 2 weeks) were randomly divided into two groups. They were administered imidapril 5-10 mg once daily or benazepril 10-20 mg once daily for six weeks, respectively. If DBP≥90 mm Hg at the end of the third week, the dosage of the drug was doubled. Imidapril group and benazepril group were crossed over at the end of the seventh week, and continued to administer imidapril or benazepril for another six weeks. Hypotensive efficacy and occurrence of cough were observed during the whole study period. Results Blood pressure decreased significantly in both groups at the stage I (before crossing-over) and Ⅱ (after crossing-over), P<0.01. There was no significant difference in antihypertensive efficacy between the two groups. The occurrence of cough in imidapril and benazepril groups was 14.5% and 24.6% at stage Ⅰ, respectively. The occurrence of cough in the two groups was 16.9% and 23.0% at stage Ⅱ, respectively. Significant difference in the occurrence of cough was found between the two groups, P<0.05. Conclusion Both imidapril and benazepril exert favourable and similar hypotensive effect, however the cough occurrence of imidapril is significantly lower than that of benazepril.