Objective： To investigate collagen remodeling in infarct zone(IZ) and non-infarct zone(NIZ) in rat model of myocardial infarction. Methods:Large myocardial infarction of left ventricle was produced in rats by ligation of left coronary artery.Collagen contents were measured with the chloramine T method and collagen type Ⅰ/Ⅲ ratios were analysed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis.The changes of collagen content and collagen type Ⅰ/Ⅲ ratio in IZ and NIZ were sequentially observed at 1,3, 7,14, and 42 d after myocardial infarction. Results: Collagen contents in IZ and NIZ increased gradually with time and were higher at 3, 7, 14 and 42 d than those in sham group at corresponding time (P<0.05). Compared with sham group,collagen type Ⅰ/Ⅲ ratio in IZ was lower at 3 d, and increased significantly after 7 d(P<0.01). The collagen type Ⅰ/Ⅲ ratio in NIZ was higher at 14 d (P<0.01) and 42 d (P<0.05). Conclusion: Collagen remodelling occured in both infarct zone and non-infarct zone after myocardial infarction,which may play an important role in the process of left ventricular remodelling after myocardial infarction.