Objective To investigate the relationship of red cell distribution width (RDW) with 1-year outcomes in the elderly with acute decompensated heart failure with preserved ejection fraction (HFpEF). Methods A total of 125 consecutive patients (≥65 years old) admitted in the cardiovascular ward of health care center of our hosipatal from June 2013 to June 2015 were enrolled in this study. Their baseline data, comorbidities, drug uses, laboratory results and echocardiographic parameters, and RDW at admission were collected and recorded. After 1 year of follow-up, the patients were divided into events group (n=38) and control group (n=87) according to whether there was cardiac-related adverse events (composite endpoint of heart failure death and heart failure re-admission). Based on the interquartile range (IQR) of RDW, the patients were also assigned into 4 groups, the clinical data and endpoint events were compared among the 4 groups. SPSS statistics 16.0 was used to perform the statistical analysis. Logistic regression analysis was used to determine the independent risk factors of acute decompensated HFpEF. Receiver operating characteristic (ROC) curve was plotted to determine cut-off value of RDW to predict adverse outcomes of heart failure. Results Compared with the control group, the RDW value was significantly higher in the events group [13.30% (12.45%, 14.43%) vs 12.70% (11.50%, 13.60%);P=0.022]. Logistic regression analysis showed N-terminal pro-B-type natriuretic peptide (NT-proBNP) (OR=1.00,5%CI:1.00-1.00; P=0.010), RDW (OR=1.19,5%CI:1.05-1.35; P=0.005) and use of loop diuretics therapy (OR=6.64,5%CI:2.10-20.94; P=0.001) were independently correlated with composite endpoint of heart failure death and heart failure re-admission. With the increase of RDW, the incidences of endpoint events were elevated (P<0.05). The area under ROC curve was 0.629 in predicting composite endpoints (95%CI:0.521-0.737; P=0.022). Conclusion RDW is independently correlated with 1-year composite outcome of heart failure death and heart failure re-admission in the elderly patients with acute decompensated HFpEF.