Introduction and objectives: The present article investigates the causes of sudden death in Spain. The data were drawn from the National Registry of Accidental and Sudden Death in Athletes. Methods: There were 180 cases of sudden death from 1995 to present. Results: 180 cases of sudden death, 166 in males, 12 in females and 4 in which gender was not recorded. Sports: football (40 cases), cycling (39), athletics (24), futsal and racquet sports (8 each) and physical education (7). The most common cases of sudden death were atheromatous coronary disease (48 cases), arrhythmogenic cardiomyopathy (11), hypertrophic cardiomyopathy (9), congenital coronary anomalies (5), idiopathic left ventricular hypertrophy (4), and aortic valvular stenosis (4). In persons aged more than 30 years old (96): atheromatous coronary disease (73.43%), arrhythmogenic cardiomyopathy (6.25%) and hypertrophic cardiomyopathy (4.68%). In deaths occurring in persons aged 30 years or less (84): arrhythmogenic cardiomyopathy (13.72%), hypertrophic cardiomyopathy (11.76%), congenital coronary anomalies (9.8%), idiopathic left ventricular hypertrophy (7.84%), and aortic valvular stenosis (5.88%). In this age group, most deaths were of undetermined cause (27.45%). Conclusions: It is difficult to obtain complete data on cases of sudden death in Spanish athletes, the incidence of which is considerable in young persons and adults in the fifth decade of life. The most commonly involved sports are football, cycling and athletics. After the age of 30 years, the most frequent cause of sudden death is atheromatous coronary disease. Below the age of 30 years, the cause with the greatest incidence is unexplained death occurring in a structurally normal heart. Mechanisms for obtaining more detailed information on the causes of sudden death in athletes should be established through this register.