The mitral valve is a living structure comprised of specific structural components which contain a heterogeneous population of cells. The cells include an amalgam of interstitial cells within the valve and a continuous covering of endothelial cells, each of which play a role in responding to the mechanical forces that the valve experiences, to maintain the function and durability of the valve. Attention on the characteristics and function of valve cells has focused mainly on those in the aortic valve, with relatively few studies addressing the role of these cells in the physiological and pathophysiological function of the mitral valve. This article reviews what is known about the function of cells within the mitral valve and how the changes in the physical and chemical environments can affect their function in the different types of mitral valve disease. Investigating the contribution of the cellular components of the mitral valve to valve function in health and disease will aid the understanding of how the durability and function of the valve are regulated, and possibly highlight molecular and pharmacological targets for the development of novel treatments for mitral valve disease.