In the industrially developed countries, sudden cardiac death is the leading cause of death. It was recognized at the dawn of recorded history and even depicted in Egyptian relief sculpture from the tomb of a noble of the Sixth dynasty approximately 4,500 years ago. Sudden cardiac death has left no age untouched. Sparing neither saint nor sinner, it has burdened man with a sense of uncertainty and fragility. The enormity of this problem demands attention. In the United States, sudden cardiac death claims about 1,200 lives daily, or approximately one victim every minute. It is the leading cause of death among men aged 20 to 64 years, accounting for 32 percent of the fatalities in this group. Nearly 25 percent of persons dying suddenly have had no prior recognized symptoms of heart disease.The excess of widows observed in retirement communities is accounted for by the three- to fourfold greater incidence of sudden cardiac death among men. Sudden death in old age might be a blessing rather than a scourge, but instead it frequently explodes a man's life at its prime, at a median age of only 59 years. The medical profession has sensed the issue but has largely ignored sudden death as a problem amenable to solution. This indifference has not been the result of a lack of interest or concern but a reflection of the belief that sudden cardiac death was the inevitable culmination of coronary atherosclerosis. Because sudden death was unpredictable and afflicted the apparently healthy subject outside the hospital, the physician considered it an act of fate before which he was largely helpless. The advent of the coronary care unit has promoted a reassessment of this complex problem. It has become clear that sudden death is not the inexorable culmination of advanced coronary atherosclerosis but instead is the result of ventricular fibrillation and therefore is readily reversible.7,8 If ventricular fibrillation were only the consequence of severe coronary atherosclerosis, once reversed it would promptly recur. However, patients treated for ventricular fibrillation seldom have recurring episodes, and they usually recover and survive for long periods.9,10 The new concept that ventricular fibrillation is an electrical accident suggests that its cause is not anatomic and thereby contributes to the growing interest in redefining the basis for sudden death and developing methods for its containment. Until recently our inability to deal with sudden cardiac death has not been due to a gap in the application of knowledge but to a gap in knowledge itself. The purpose of this review is to indicate how much we know and to sketch the path of possible further progress. © 1979.