OBJECTIVE:To study the effects of salvianolic acid B(Sal B)on angiotensin Ⅱ(Ang Ⅱ)-induced cardiac fibro-blast proliferation,secretion of type Ⅲ collagen,protein expressions of matrix metalloproteinase 9 (MMP-9),Smad2/3,Smad7, and explore its mechanism of anti-myocardial fibrosis. METHODS:Cells were divided into blank control group(culture medium) Ang Ⅱ model group,Sal B low-dose,medium-dose,high-dose groups (12.5,25,50 μmol/L). After cultured 1 h by blank or drug-containing culture,except for blank control group,cells in other groups were added 1 μmol/L Ang Ⅱ to induce proliferation. for 24 h. MTT method and hematoxylin-eosin staining method were adopted investigate the effect of Sal B on proliferation. Western blot method was adopted to detect the effects of Sal B on protein expressions of type Ⅲ collagen,MMP-9,Smad2/3,Smad7. RE-SULTS:Compared with blank control group,cells in Ang Ⅱ model group were significantly proliferated,protein expressions of type Ⅲ collagen,MMP-9,Smad2/3 were obviously enhanced,protein expression of Smad7 was obviously weakened,with statisti-cal significances(P<0.05). Compared with Ang Ⅱ model group,the cell proliferation in Sal B groups were inhibited,protein ex-pressions of typeⅢcollagen,MMP-9,Smad2/3 were weakened,while protein expression of Smad7 was enhanced. Except the pro-tein expression of type Ⅲ collagen in Sal B low-dose and medium-dose groups,the protein expression of Smad2/3 in Sal B high-dose group did not change significantly,other indexes had statistical significances(P<0.05). CONCLUSIONS:The anti-myo-cardial fibrosis effect of Sal B may be associated with inhibiting the proliferation of cardiac fibroblasts,down-regulating protein ex-pressions of typeⅢcollagen,MMP-9,Smad2/3 and up-regulating protein expression of Smad7.