A 56-year-old man visited a doctor because of arrhythmia and a diagnosis of hypertrophic cardiomyopathy was made in 1990. On January 9th, 1997, when aged 63 years old, he visited another doctor because of paroxysmal atrial fibrillation tachycardia. Since his clinical symptoms did not ameliorate, he visited our hospital on April 14th, and Holter electrocardiographic monitoring was started on April 16th. While walking on the street, his heart rate increased up to 107 beat/min when premature ventricular contraction with a long coupling interval of 400 msec occurred, followed by polymorphous ventricular tachycardia, ventricular fibrillation and death. He had no risk factors for sudden death such as early onset of symptoms, history of syncope, family history of sudden death, documented ventricular tachycardia, and congestive heart failure. Although many cases of hypertrophic cardiomyopathy end in sudden death, no electrocardiographic recordings at the time of sudden death have been available. This is the first case of electrocardiographic recording at the time of sudden death in a patient with hypertrophic cardiomyopathy.