Cilostazol is being developed for the treatment of intermittent claudication due to peripheral arterial disease (PAD). This study was conducted to investigate the effects of age and gender on the pharmacokinetics of cilostazol after multiple-dose administration. It was an open label, multiple-dose study of cilostazol administered to male and female subjects 50 years of age and older at a dose of 100 mg (oral tablet) twice daily for 7 days. Equal numbers of healthy male and female (7 per group), nonsmoking subjects stratified into age groups of 50 to 59 years, 60 to 69 years, and 70 years or older were enrolled. Serial plasma samples were obtained. Data were analyzed by model-independent methods. Cilostazol was absorbed at a moderate rate, with peak plasma concentrations occurring at an overall mean of 2.4 hours after administration. Cilostazol is extensively bound (95%), primarily to albumin. A trend toward increasing cilostazol free fraction with age was observed in the male subjects, which was explained by a decrease in plasma albumin concentration with age. Differences in plasma protein binding between age and gender groups (less than 15%) are not expected to have any clinical significance. Plasma cilostazol concentrations reached steady state by day 4. The pharmacokinetic characteristics of cilostazol were not affected by age or gender.