Abstract: Aim\ To assess the clinical efficacy and safety of fosinopril in the treatment of isolated systolic hypertension in the elderly（ISH）.\ Methods\ Fosinopril was used in the treatment of 56 mild to moderate patients with ISH,5～20 mg per day for 6 weeks,with the observation of casual blood pressure（CBP） and ambulatory blood pressure monitoring（ABPM）.\ Results\ Effective rate was 911%.\ Trough to peak ratio of SBP and DBP was 735% and 528%,respectively.\ After therapy,24 h mean SBP（24hS）, minimal SBP（Min S）,maximal SBP（Max S）,day mean SBP（dS）,night mean SBP（nS） and blood perssure burden（S＜140） were significantly reduced（P＜001）; 24 h mean DBP（24hD）, maximal DBP（MinD） and night mean DBP（nD） were markedly reduced too（P＜005）.\ The incidence of adverse effects was 233%.\ Conclusion\ Fosinopril is effective,safe and well tolerated in patients with ISH.