Background-Growth-differentiation factor-15 (GDF-15) is a stress-responsive transforming growth factor-beta-related cytokine that has emerged as a prognostic biomarker in acute coronary syndrome trial populations. Its predictive role in stable coronary heart disease (CHD) has never been assessed. Methods and Results-The circulating levels of GDF-15 were measured by immunoradiometric assay in patients with stable angina pectoris (n = 1352) or acute coronary syndrome (n = 877) who were followed up for a median of 3.6 years. Stable angina pectoris patients presenting with normal (<1200 ng/L), moderately elevated (1200 to 1800 ng/L), or markedly elevated (>1800 ng/L) GDF-15 levels had 3.6-year CHD mortality rates of 1.4%, 2.7%, and 15.0%, respectively (P < 0.001). By backward stepwise Cox-regression analysis, which adjusted for age and gender, clinical variables, the number of diseased vessels, renal function, the levels of C-reactive protein, cardiac troponin I, and N-terminal pro-B-type natriuretic peptide, GDF-15 remained an independent predictor of CHD mortality (P < 0.001). Addition of GDF-15 improved the prognostic accuracy of a clinical risk prediction model concerning CHD mortality (c-statistic, 0.84 versus 0.74; P = 0.005). Analysis of the acute coronary syndrome part of the study population confirmed GDF-15 as an independent predictor of CHD mortality (P < 0.001). The circulating levels of GDF-15 did not predict the future risk of nonfatal myocardial infarction in patients with stable angina pectoris or acute coronary syndrome. Conclusion-This study identifies GDF-15 as a strong and independent predictor of CHD mortality across the broad spectrum of patients with stable and unstable CHD. (Circ Cardiovasc Genet. 2009; 2: 286-292.)