Background and Objectives: Anemia is frequently observed in patients with reduced left ventricular ejection fraction (LVEF) and might be associated with increased mortality. However, the prognostic effect of anemia was still not concluded in patients with heart failure associated with preserved LVEF (HF-PEF) or diastolic heart failure. The aim of this study was to assess the effect of anemia on mortality in HF-PEF. Subjects and Methods: The Korean Heart Failure Registry (KorHFR) prospectively studied the characteristic and outcomes in a broadly sampled patients hospitalized with worsening HF and the outcomes were followed by 24 university centers in South Korea. Of the total cohort of HF 3,200 patients, 708 (24.9%) patients with preserved LVEF (50%) were analyzed. We compared the mortality rate between patients with anemia [female hemoglobin (Hb) < 12.0 g/dL, male Hb < 13.0 g/dL by WHO definition] (anemia group) and patients without anemia (non-anemia group). We also analyzed the mortality rate between patients divided into 4 quartiles based on Hb level: Hb < 10.5(Group 1); Hb 10.5-12.0(Group 2); Hb 12.0-13.6(Group 3); Hb > 13.6 g/dL(Group 4). Results: Anemia was found in 380 (53.7%) patents. The total mortality rate was 16.7%. Mortality was higher in anemia group (anemia group 21.8%, non-anemia group 10.7%, p <0.001). Mortality was higher with lower Hb quartile (30.5%, 14.7%, 13.0%, 8.5% for each quartile, p <0.001). Conclusions: Anemia was associated with an increased mortality. Therefore, anemia in patients with HF-PEF should be considered as a useful prognostic factor, and the target of treatment. Key Words: Anemia, Heart failure with preserved LV ejection fraction, Mortality