Objective To investigate the efficacy of cardiac resynchronization therapy (CRT) and the correlation of red blood cell distribution width (RDW) with the response to CRT. Methods A retrospective analysis was carried out on 45 patients with chronic heart failure (CHF) undergoing implantation of CRT-pacing/defibrillation (P/D) in the Heart Center of the First Hospital of Lanzhou University from October 2007 to March 2016. According to their responses to CRT, they were divided into response group (n=27) and non-response group (n=18). Their clinical data before operation and in 6 months postoperatively were collected and analyzed. Multivariate logistic regression analysis was used to explore the factors influencing the response to CRT. Results There were 27 responders in the subjects, with a respondent rate of 60%. Significant differences were observed in the patients in different classes by the New York Heart Association (NYHA) functional classification from the both groups after CRT (P<0.05). In comparison to the data before treatment, the responder group got great improvements in the heart functional class, left ventricular ejection fraction (LVEF), left ventricular end diastolic diameter (LVEDD), left ventricular end diastolic volume (LVEDV), QRS duration (QRSd), 6-minute walking distance (6MWD) and Minnesota quality of life questionnaire (MLHFQ) (all P<0.05). Obvious improvements were only seen in LVEF, LVEDD, and QRSd in the non-responder group (all P<0.05). Between these 2 groups, there were significant differences in the NYHA functional class and LVEF after CRT (P<0.05). Pre-operative NYHA functional class, QRSd before CRT≥150 ms, the amount of QRS shortening (ΔQRSd), RDW before CRT and CRT-D were the independent factors for the response to CRT (P<0.05). Conclusion Evaluating NYHA functional class, QRS complex and RDW is very important before the CRT treatment, and these indicators are of great significances for the response to CRT.