Aims. To examine the association between heart-rate corrected QT prolongation and cardiac and all-cause mortality in the population-based Rotterdam Study among men and women aged 55 years or older and to compare the prognostic value of the QT interval, using different formulas to correct for heart rate. Methods and Results. After exclusion of participants with arrhythmias or bundle branch block on the EGG, the study population consisted of 2083 men and 3158 women. The QT interval was computed by the Modular ECG Analysis System (MEANS). Data were analysed using Cox' proportional hazards model. Participants in the highest quartile of the heart-rate corrected QT interval had about a 70% age- and sex-adjusted increased risk for both all-cause mortality (hazard ratio (HR) 1.8; 95%CI:1.3-2.4) and cardiac mortality (HR) 1.7; 95%CI:1.0-2.7) compared to those in the lowest quartile. In women, the increased risk associated with prolonged QT for cardiac death was more pronounced than in men. These risk estimates did not change after adjustment for potential confounders, including history of myocardial infarction, hypertension and diabetes mellitus. Conclusion. A prolonged heart-rate corrected QT interval is an independent predictor for cardiac and all-cause mortality in older men and women. The risk associated with prolonged QT is hardly affected by the heart-rate correction formula used.