BACKGROUND: Diagnosing heart failure with preserved ejection fraction (HFpEF) is challenging. Although the H2FPEF score and HFA-PEFF algorithm have been proposed for diagnosing HFpEF, previous validation studies were conducted in stable chronic heart failure (HF). Moreover, information on their applicability in the Asian population is limited. We sought to investigate these scores' diagnostic performance for HFpEF in Japanese patients recently hospitalized due to acute decompensated HF. METHODS: We examined patients with HFpEF recently hospitalized with acute decompensated HF from a nationwide HFpEF-specific multicenter registry (HFpEF group) and control patients who underwent echocardiography to investigate the cause of dyspnea in our hospital (Non-HFpEF group). RESULTS: The studied population included 372 patients (194 HFpEF group and 178 Non-HFpEF group; HFpEF prevalence, 52%). A high H2FPEF score (6-9 points) could diagnose HFpEF with a high specificity of 97% and a positive predictive value (PPV) of 94%, and a low H2FPEF score (0-1 point) could rule out HFpEF with a high sensitivity of 97% and a negative predictive value (NPV) of 93%. HFpEF could be diagnosed with a high HFA-PEFF score (5-6 points) (specificity, 84%; PPV, 82%) or ruled out with a low HFA-PEFF score (0-1 point) (sensitivity, 99%; NPV, 89%). The H2FPEF score was significantly superior to the HFA-PEFF score in diagnostic accuracy (area under the curve: 0.89 vs. 0.82, respectively, p = 0.004). CONCLUSIONS: The H2FPEF and the HFA-PEFF scores had acceptable diagnostic accuracy in diagnosing HFpEF in Japanese patients.