Asymmetric septal hypertrophic cardiomyopathy (ASH) is the common phenotype of hypertrophic cardiomyopathy (HCM). We sought to classify ASH using magnetic resonance imaging (MRI) and to determine whether the MRI classification of ASH is related to the presence of risk factors for HCM. Ninety-three patients with ASH underwent cine and delayed-enhancement MRI. The ASH was classified morphologically using cine MRI at end-diastole. We evaluated the association between the MRI findings and the presence of risk factors in the ASH. The ASH was classified into three subtypes by MRI: contiguous subtype showing various clinical and MRI features (57%), sigmoid subtype (29%) with fewer risk factors, and reverse-curve subtype (14%) in younger patients with the larger myocardial mass and delayed-enhancement, which were significantly related to the risk factors. MRI was used to classify ASH into three subtypes, which might be related to the presence of risk factors.