A 36-year-old woman with hypertrophic cardiomyopathy (HCM) was referred for the evaluation of chest pain. A stress cardiac magnetic resonance showed severe hypertrophy of the anteroseptal wall with severe ischaemia induced after adenosine infusion. LV size and function were normal. On delayed enhancement imaging, extensive, patchy areas of hyperenhancement in the hypertrophic segments were observed. A 64-slice computed tomography scan showed no evidence of significant coronary disease. Microvascular dysfunction in HCM may be a predisposing factor for myocardial ischaemia, leading to an increased risk of sudden death. However, the pathophysiological mechanisms remain largely unknown as well as whether the extension of the hypertrophy is associated with poor perfusion reserve. Non-invasive imaging modalities may be helpful in the identification of the underlying substrate determining the risk in these patients.