AIM: To investigate 1) the role of transforming growth factor-?_1(TGF-?_1) and macrophage infiltration during the development of myocardial fibrosis(MF) in rats after myocardial infarction(MI);and 2) mechanisms of MF post-MI and the inhibitory effect of angelica.METHODS: Sprague-Dawley(SD) rats were subjected to MI by ligating the left anterior descending coronary artery.The animals were randomly divided into three groups: sham,MI and MI+angelica.After 24 hours of ligation,rats received angelica(20 mL?kg~(-1)?d~(-1),ip) or saline.Left ventricular hemodynamics were measured and rats were killed at week 1,week 2 and week 4, respectively.Collagen content,macrophage infiltration and TGF-?_1 expression were examined in the non-infarcted area.RESULTS: ① In MI group,the numbers of macrophage and TGF-?_1 expression were significantly upregulated compared to sham at week 1 post-MI and remained elevated at week 4(P