Calcification of the mitral annulus developed in a patient while undergoing dialysis. The rapid onset of events corresponded to the onset of end-stage renal failure and uncontrolled secondary hyperparathyroidism. Sequential echocardiograms verified the progression of calcification of the annulus as well as the valve. A new systolic and diastolic murmur and reduced valve orifice on two-dimensional echocardiography suggested acquired nonrheumatic mitral stenosis and insufficiency. We propose that metastatic calcium deposition rather than long-term hypertensive and degenerative effects was the predominant mechanism for massive calcification of the annulus and valve. It is suggested that M-mode echocardiography be used sequentially to follow both the occurrence and progression of calcification of the mitral annulus or valve in patients with chronic renal failure, secondary hyperparathyroidism, or both.