From 1978 to 1993 in the Veneto region, we collected 200 cases of sudden death in the young (</=35 years). Sudden death was cerebral in 15 cases (7.5%), respiratory in 10 (5%), and cardiovascular in 163 (81.5%), whereas it remained unexplained in 12 cases (6%). Among cardiovascular sudden death, obstructive coronary atherosclerosis accounted for 23% of cases, arrhythmogenic right ventricular cardiomyopathy for 12.5%, mitral valve prolapse for 10%, conduction system abnormalities for 10%, congenital coronary artery anomalies for 8.5%, myocarditis for 7.5%, hypertrophic cardiomyopathy for 5.5%, aortic rupture for 5.5%, dilated cardiomyopathy for 5%, nonatherosclerotic-acquired coronary artery disease for 3.5%, postoperative congenital heart disease for 3%, aortic stenosis for 2%, pulmonary embolism for 2%, and other causes for 2%. Cardiac arrest remained unexplained in 6% of the cases. Specific pathology and pathogenetic mechanisms of each disease were investigated and correlated with clinical signs and symptoms in detail. A large spectrum of cardiovascular disorders, both congenital and acquired, may represent the organic substrate of sudden death in the young. The underlying abnormality is frequently concealed and discovered only at postmortem examination. Most of the diseases, although asymptomatic, are potentially detectable during life with proper imaging tests.