Objective: Anchoring cardiac myocytes to extracellular matrix, which is mediated mainly by integrins on their surfaces, is important for maintaining the architecture of myocardial tissues and transmitting mechanical force. We evaluated the expression of α integrin subunits on myocytes and the accumulation of interstitial collagen and fibronectin at acute and chronic stages after myocardial infarction. Methods: Myocardial infarction was induced by ligation of left coronary arteries in rats. The expression of α1, α3 and α5 integrin subunits, and accumulation of collagen and fibronectin were analyzed with immunohistochemistry or sirius-red staining. Results: In hearts without infarction, moderate expression of the α3 subunit and only slight expression of the α5 subunit were observed on myocytes. In the first week after infarction, the α1 subunit, collagen and fibronectin were increased only in the peri-infarcted area, while the α5 subunit was increased both in peri-infarcted and non-infarcted areas. At day 42, the expression of the α1 subunit and collagen were still increased, although the α5 subunit and fibronectin were decreased. The expression of the α3 subunit was not altered throughout the experimental period. Conclusion: These data suggest that integrin subunits play an important role in healing and remodeling processes after myocardial infarction.