Canstatin, a cleaved C-terminal fragment of type IV collagen α2 chain, inhibits hypoxia-induced apoptosis in H9c2 cardiomyoblasts. After myocardial infarction, the expression of canstatin is decreased in the infarcted area. We investigated whether the canstatin-treatment exerts a cardioprotective effect on heart failure after myocardial infarction in rats. The myocardial infarction model rats induced by ligating left anterior descending artery were intraperitoneally injected with recombinant canstatin (20 µg/kg/day) or vehicle for 28 days after the operation. Echocardiographic analysis showed that canstatin-treatment significantly inhibited cardiac dysfunction and tended to inhibit left ventricular dilation. Canstatin did not change the ratio of infarcted area to left ventricular area. In the histological analysis of non-infarcted area, canstatin inhibited hypertrophy of cardiomyocytes (using hematoxylin and eosin staining) and interstitial fibrosis (using picro-sirius red staining). The present study for the first time demonstrated that chronic recombinant canstatin-treatment prevents heart failure after myocardial infarction through the inhibition of cardiac hypertrophy and fibrosis in non-infarcted area.