We evaluated 4 patients who developed severe, symptomatic stridor during maximal cardiopulmonary exercise testing, all referred due to exercise-related dyspnea. All underwent resting, unsedated transnasal fiberoptic laryngoscopy and had normal findings. Four patients performed repeat maximal exercise testing with fiberoptic laryngoscopy, and they form the basis of this report. They had normal vocal cord motion during exercise, but developed abnormal anterior motion of the arytenoid and aryepiglottic folds only at peak exercise, leading to partial airway obstruction and severe stridor. This report details the workup and characterizes patients at risk for this unusual phenomenon.