Twenty-two young adult (mean age 27.8 +/- 5.3 years) survivors of sudden cardiac arrest underwent invasive cardiac assessment. Initial evaluation by cardiac catheterization, coronary angiography, and hemodynamic studies identified two groups of young survivors. The first consisted of 13 (60%) subjects who had definable structural cardiac or lung disease accountable for a cardiac arrest event. Dilated cardiomyopathy dominated this group. Mitral valve prolapse, hypertrophic cardiomyopathy, left ventricular hypertrophy, anomalous origin of the right coronary artery, and tetralogy of Fallot were also encountered. The second group included nine subjects (40%) with normal cardiac structure and normal hemodynamic parameters. Electrophysiologic testing demonstrated in three of these patients the presence of Wolff-Parkinson-White syndrome. The electrophysiologic studies had a higher yield in reproduction of life-threatening arrhythmias among the subjects in the second group as opposed to the first group. The observation that 10 subjects (45%) from both groups had preceding symptoms varying from palpitations and chest pain to syncope and recurrent cardiac arrest events, is in contradiction to previous findings in the literature and raises a question of appropriate evaluation of young adults with cardiac symptoms.