Restrictive cardiomyopathy (RCM) is defined on the basis of the haemodynamic finding of restrictive ventricular physiology. However, restrictive ventricular pathophysiology is also a feature of other subtypes of cardiomyopathy, including hypertrophic cardiomyopathy (HCM). Clinically and aetiologically, there is an overlap between RCM and HCM with restrictive physiology. However, the clinical distinction between these two entities can be an important pointer towards the underlying aetiology. This review highlights the importance of the recognition of the clinical phenotype as the first step in the classification of cardiomyopathies