Aim [WT5”BZ]To investigate the relationship between the clinical effects of defibrase on acute cerebral infarction and the time used, and the effect on the platelet aggregation and fibrinogen in the patient`s blood. [WT5”HZ]Methods [WT5”BZ]Divide the 72 cases of acute cerebral infarction (ACI) confirmed by CT scan into the defibrase group (38 cases) and the Radix Salviae Miltorrhizase (RSM) group (34 cases). The defibrase group were treated with defibrase iv drip of 10 units mixed 250 mL of physiological saline q.d. for 3 days. The RSM group were treated with RSM iv drip of 0.4 g mixed with 250 mL of 5% glucose q.d. for 14 days. The platelet aggregation function and the fibrinogen of the patients` blood were measured both before and after the drug was given. The clinical effects were valved at the end of the 1st week and the 4th week.[WT5”HZ] Results [WT5”BZ]Before the drug was gevin the platelet aggregation rate was 65.6%±5.3% and the fibrinogen was 4.78±0.42 g/L in the defibrase group, after the drug was given, the platelet aggregation rate was 45.8%±4.9% and the fibrinogen was 3.16±0.35 g/L with a significant difference (P<0.001).Before the drug was given the platelet aggregation rate was 60.4%±1.9% in the RSM group, after the drug was given the platelet aggregation rate was 49.0%±10.3% with a significant difference (P<0.01). [WT5”HZ] Conclusions [WT5”BZ] Defibrase is superior to RSM in controlling the platelet aggregation function and decreasing the plasma fibrinogen concentration, which improves the patient`s high viscosity state and prevents the thrombosis.