Objective To investigate the clinical characteristics of acute pulmonary embolism in the elderly and its differences between the elderly and non-elderly patients,and explore the predictive effect of red blood cell distribution width(RDW)on chronic thromboembolic pulmonary hypertension (CTEPH)in patients with acute pulmonary embolism.Methods A total of 129 consecutive patients with acute pulmonary embolism admitted into Affiliated Hospital of Binzhou Medical College were selected from Jan.2009 to Dec.2013.Clinical data including the basic data,blood routine test,blood gas analysis,Doppler echocardiography during admission were retrospectively analyzed.All the patients were followed-up.Ancillary findings and changes of the disease were recorded in detail during the follow-up period.SPSS 19.0 was used to analyze the results.Results The incidences of CEPPH and venous thromboembolism(VTE)in APE patients were higher in the elderly than in non-elderly.The mean RDW and pulmonary arterial systolic pressure on admission in APE patients were higher in the elderly than in non-elderly [(14.22±2.11)％ vs.(13.48± 1.69)％,P=0.033,for mean RDW] and [(54.82± 21.77)mmHg vs.(42.20 ± 19.36) mmHg,P=0.010 for pulmonary arterial systolic pressure].The mean RDW was higher in CTEPH patients than in patients without CTEPH [(16.79 ± 3.08) ％ vs.(13.68± 1.68)％,P=0.016].Multivariate Logistic analyses showed that the increased RDW level was an independent risk factors for CTEPH in APE patients(OR=1.535,95％ CI:1.094-2.155,P=0.013).The area under receiver operating characteristics curve(AUC)of RDW level for predicting CTEPH in APE patients was 0.856(95％ CI:0.706-0.987,P＜0.001),the corresponding cut-off point was 14.85％,and the sensitivity and specificity were 88.9％ and 87.5％ respectively.Conclusions The increased RDW level could predict the risk of CTEPH to a certain extent in APE patients.