A previously healthy young woman who developed the new onset of symptomatic sustained ventricular tachycardia during pregnancy is described. Evaluation revealed mitral valve prolapse with minimal mitral regurgitation, and normal left ventricular size and function. The arrhythmia resolved after delivery, but recurred nine months later in a nonsustained form. Electrophysiologic study revealed only nonsustained ventricular tachycardia, and she was treated with propafenone. It is suggested that the pregnant state may have been important in the pathogenesis of her arrhythmia.