Background and Objective To investigate the effects of simvastatin on lipid lowering therapy and platelet activation in elderly patients with hypercholesterolemia. Methods Fasting serum lipids, CD63, CD41a, serum glucose, hepatic and renal function, routine urine analysis (UA) were measured in 50 healthy subjects, and in 50 elderly patients with hypercholesterolemia before and after 4 weeks treatment with simvastatin (20mg daily for 4 weeks). Results 1. After simvastatin treatment for 4 weeks, the fasting serum level of lipids in elderly patients with hypercholesterolemia was significantly lower than before treatment (P＜0.01). 2. CD63 and CD41a were decreased after treatment compared with before, respectively (1.36 0.34) vs (4.26 1.06), (P＜0.01) and (123.54 19.73) vs (253.78 16.75), (P＜0.01).3. Changes in serum lipid level tended to be positively correlated with the declines in CD63 and CD41a, but there was no statistical significance (P＞0.05). Conclusions The results suggested that lipid lowering therapy with simvastatin inhibit platelet activity.