Calcification of the mitral valve annulus is a chronic degenerative process commonly seen in the older age group. In developing countries like India, it can occur in later stages of rheumatic heart disease. Caseous calcification (CC) of the mitral annulus is a less described atypical variant of mitral valve calcification commonly reported in the basal area of the posterior mitral leaflet in elderly patients with degenerative diseases. The peculiarity of our case is the early age of development, i.e., CC had developed in a 15-year-old male patient with rheumatic heart disease diagnosed by echocardiography and helped in further management.