Hypertrophic cardiomyopathy (HCM) is characterized by a hypertrophic, non-dilated left ventricle. With a prevalence of approximately 0.2% in humans and 15% in cats, this is one of the most common heart diseases. The disorder is often inherited but may also be acquired during life. The clinical symptoms may differ. Genotypically affected individuals can exhibit (severe) symptoms of heart failure or die suddenly, but they can also stay asymptomatic during their entire life. More than 1400 gene polymorphisms have already been detected in thirteen genes that code for sarcomere proteins in the heart in humans. Some of them are, together with modifying genes and environmental factors, responsible for the development of HCM. To date, only three mutations have been identified in cats. Commercial tests are already available to diagnose them. These mutations are responsible for only a small fraction of the cases of HCM in cats. It is important to identify as many mutations as possible in order to develop a control strategy. There are a lot of common grounds between the human and feline forms of HCM. There are similarities in the mode of inheritance (autosomal), the clinical appearance and the histopathological changes. Still, there is not enough known about sarcomere proteins and their mutations to extrapolate information from humans to cats and vice versa.