Objective:To investigate the effect ofLeech Capsule on stability ofcarotid plaque and expression ofplatelet membrane glycoprotein in patients with cerebral arteriosclerosis.Methods:203 patients with cerebral arteriosclerosis which with unstable carotid plaque were divided into two groups.There were 101 patients in observation group which were treated by conventional therapy and Leech Capsule, and 102 patients in control group which were treated only by conventional therapy.Then comparison analysis ofIMT, plaque area, unstable plaque number and positive rates ofPAC-1 and CD62P were made before and after treatment with two groups.Results:After treatment, the IMT, plaque area, unstable plaque number and positive rates ofPAC-1 and CD62P in observation group were significantly lesser than those in control group.In observation group, all parameters after treatment were significantly lesser than those before treatment, but in control group there were no significant difference in IMT and positive rates ofCD62P between after treatment and before treatment.In addition, there were no obvious adverse reactions after treatment by leech capsule.Conclusion:Leech Capsule was an effective drug for stabilizing carotid plaque and depressing the level ofplatelet activation, and it had few adverse reaction.It was worth further spreading.