Pulsus alternans is a well-recognized clinical entity in which alternating strong and weak pulses are detected. It usually is secondary to underlying myocardial failure. Murmur alternans (alternation in murmur intensity) has been described in aortic stenosis and a few right-sided lesions such as pulmonary hypertension and embolism. This report describes a case of murmur alternans in critical pulmonary stenosis that also showed Doppler alternans on echocardiography. The underlying cause was right ventricular systolic dysfunction.