Caseous calcification of the mitral annulus is a rare form of chronic degenerative process in the mitral valve fibrous ring with a mass-like appearance that has to be in the differential of the radiologist and cardiologist. We present the case of an 82-year-old woman in whom a tumor-like calcified mass in the posterior side of the mitral valve annulus was detected at echocardiography, and the diagnosis of caseous calcification was confirmed on multidetector computed tomography (MDCT). The diagnostic features of this rare cardiac mass are described.