Little is known about the relationship between cardiac function and myocardial fiber structure after myocardial infarction (MI). We hypothesized that post-MI remodeling of left ventricular fiber structure would be reflected in changes in the regional strains. Strains and cardiac fiber structure were measured using MRI in five rats with MI, and three sham-operated rats. Transmural variation in fiber helix angles was reduced adjacent to the infarct. This reduction was associated with reduced radial, longitudinal, and endocardial circumferential strain, and improved epicardial circumferential strain in the adjacent zone. Our findings emphasize the relevance of cardiac fiber structure remodeling after myocardial infarction.