The baseline electrocardiograms of 5,125 original subjects of the Framingham Heart Study were measured to examine the relation of the QT interval corrected for heart rate (QTc) to risk of total mortality, sudden cardiac death, and death due to coronary artery disease over a 30-year follow-up period. Quintiles of QTc (seconds) less than or equal to 0.36, 0.36 to 0.38, 0.39 to 0.40, 0.41 to 0.43 and greater than or equal to 0.44 were studied in relation to these outcomes. There were no significant differences in the risk of total mortality, sudden cardiac death or death due to coronary artery disease according to QTc. A similar lack of significant association between QTc and these 3 outcomes was observed among all persons studied and in the 2 sexes after using a multiple regression analysis to control for several potentially confounding characteristics including age, gender, cigarette smoking, serum total cholesterol, systolic systemic blood pressure and Framingham relative weight. The results of this study fail to demonstrate an association between baseline QTc and overall mortality, and deaths due to sudden cardiac events or coronary artery disease in a large population-based cohort of essentially healthy persons in whom pathologic forms of QTc prolongation are uncommon.