Hypertrophic cardiomyopathy, which is morphologically defined by hypertrophy of a non-dilated ventricle, is the most common heart disease in the cat. Advances have been made with respect to the understanding of the cause, clinical presentation and distribution of this disease; however, much remains to be discovered. In this article, the cause, epidemiology, pathophysiology and therapy of feline hypertrophic cardiomyopathy are reviewed. Information that has come to light since this topic was last addressed in this series is emphasized.