Fibrotic lesions in the myocardium exhibit delayed contrast enhancement (DCE) on MR images. On the other hand, plexiform fibrosis is observed in hypertrophic cardiomyopathy (HCM), indicating an association of this condition with the pathogenesis of heart failure and arrhythmia. To examine the occurrence and extent of DCE and its relation to cardiac function and arrhythmia in HCM, we studied 59 patients with HCM who had undergone MRI. The relationship of DCE to cardiac function and arrhythmia was further investigated. DCE occurred in 45 (76.3%) of the 59 patients with HCM, with a high frequency of localization in regions, where the right ventricle is attached. As for the relationship of DCE to cardiac function, a significant decrease (P=0.007) in cardiac function was observed in the group in which 4 or more segments exhibited DCE, compared with the group in which DCE was observed in 3 or less segments. Regarding the relationship of DCE to arrhythmia, both the occurrence of DCE and the extent of DCE were significantly larger (p<0.05, p=0.026, respectively) in the group with VT. These results indicate that DCE may save to identify severe cases of HCM on the basis of cardiac function, arrhythmia, and pathophysiological aspects.