AIM: To evaluate the integrity of the coronary microvasculature in patients with hypertrophic cardiomyopathy (HCM) using first-pass magnetic resonance perfusion imaging. MATERIALS AND METHODS: Twenty-two patients with HCM and 13 healthy volunteers underwent cardiac magnetic resonance imaging (CMR) at rest. Imaging protocols included short axis cine, first-pass myocardial perfusion, and late-phase contrast-enhanced imaging. Left ventricular end-diastolic wall thickness (EDTH), myocardial thickening, maximal upslope of time-intensity curve (slope(max)), and late myocardial gadolinium enhancement (LGE) were assessed for each myocardial segment. The differences in slope(max), myocardial thickening, and EDTH between healthy volunteers and HCM patients were evaluated as were differences among hypertrophic segments of different severities (mild, moderate, and severe hypertrophy) in a one-way analysis of variance analysis. The differences in slope(max), myocardial thickening, and EDTH between the segments with and without LGE were compared by independent-sample t-test. A Pearson correlation test was used to determine the relationships between slope(max), EDTH, and myocardial thickening. RESULTS: Slope(max) was statistically significantly less in HCM patients; the degree of myocardial thickening was also significantly reduced (p < 0.001). Slope(max) and the degree of thickening statistically significantly decreased with increasing degrees of myocardial hypertrophy (p < 0.05). Differences in slope(max), myocardial thickening, and EDTH were observed between segments with and without LGE (p < 0.05). Slope(max) and myocardial thickening were negatively correlated with EDTH. CONCLUSION: First-pass myocardial perfusion CMR with slope(max) measurements demonstrates microvascular coronary dysfunction in patients with HCM, a determination that may aid in risk stratification, therapeutic planning, and determination of prognosis for HCM. (c) 2013 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.