Abstract Objectives This study aimed to determine if changes in myeloperoxidase (MPO) levels correlate with response to cardiac resynchronization therapy (CRT) and the potential role of MPO as a predictor of response to CRT. Background CRT is a well-established treatment option in chronic heart failure (CHF) with 50–80% of patients benefiting. Inflammation and oxidative stress play a key role in CHF pathophysiology. Previous studies have demonstrated increased levels of MPO in CHF patients, but the correlation with CRT response remains incompletely understood. Methods Fifty-three patients underwent CRT implantation. During follow-up, patients were divided into two groups, responders and non-responders to CRT, based on improved physical capacity and NYHA classification. Levels of MPO and NT-pro-brain-natriuretic-peptide (NT-proBNP) were determined prior to implantation, 30 and 90 days after. Physical capacity, including a 6-min walking-test, NYHA class, and LVEF were evaluated at baseline and during follow-up. Results Thirty-four patients (64%) responded to CRT, showing improved physical capacity and LVEF. All responders revealed a significant decrease of MPO levels (503.8 ng/ml vs. 188.4 ng/ml; p < 0.001). Non-responding patients did not show any significant changes in clinical parameters or MPO levels (119.6 ng/ml vs. 134.3 ng/ml; p = 0.672) during follow-up. At baseline, physical capacity and NYHA class, as well as MPO levels differed significantly between both groups (p < 0.001). A ROC analysis identified an MPO cut-off value for response to CRT of 242 ng/ml with a sensitivity of 93.5% and specificity of 71.4%. There was a strong correlation between MPO and improvement of LVEF (Spearman’s rho: − 0.453; p = 0.005) and physical capacity (Spearman’s rho: − 0.335; p = 0.042). Conclusions Response to CRT and course of MPO levels correlate significantly. MPO levels differ between responders and non-responders prior to CRT, which may indicate an additional value of MPO as a predictor for CRT response. Further randomized studies are required to confirm our data in larger patient cohorts.