Abstract Background Anemia is a predictor of adverse outcomes in acute myocardial infarction. We studied the relationship of hemoglobin, or its change over time, and outcomes in patients with stable coronary artery disease. Methods CLARIFY is a prospective, cohort study of outpatients with stable coronary artery disease (32,901 in 45 countries 2009-2010); 21,829 with baseline hemoglobin levels. They were divided into hemoglobin quintiles and anemia status (anemic A or normal N) at baseline/follow-up: N/N; A/N; N/A; A/A. All-cause mortality, cardiovascular events, and major bleeding at 4-year follow-up were assessed. Results Low baseline hemoglobin was an independent predictor of all-cause, cardiovascular, and noncardiovascular mortality, the composite of cardiovascular death/myocardial infarction or stroke and major bleeds (all P <.001; unadjusted models). Anemia at follow-up was independently associated with all-cause mortality (hazard ratio HR, 1.90; 95% confidence interval CI, 1.55-2.33 for A/A; 1.87; 1.54-2.28 for N/A; both P <.001), noncardiovascular mortality ( P <.001), and cardiovascular mortality ( P = .001). Patients whose baseline anemia normalized (A/N) were not at increased risk of death (HR, 1.02; 95% CI, 0.77-1.35), although risk of major bleeding was greater (HR, 2.06; 95% CI, 1.23-3.44; P = .013) than in those with normal hemoglobin throughout. Sensitivity analyses excluding patients with heart failure and chronic kidney disease at baseline yielded qualitatively similar results. Conclusion In this large stable coronary artery disease population, low hemoglobin was an independent predictor of mortality, cardiovascular events, and major bleeds. Persisting or new-onset anemia is a powerful predictor of cardiovascular and noncardiovascular mortality.