SUMMARY OBJECTIVE: The aim of this study was to investigate the relationship between the development of deep sternal wound infection after open heart surgery and inflammatory parameters obtained from routine biochemical tests. METHODS: A total of 280 patients who underwent cardiac surgery with median sternotomy between January 2015 and January 2020 were examined retrospectively. Patients who developed deep sternal wound infection were identified as “Group 1,” and those who did not develop deep sternal wound infection were identified as “Group 2.” RESULTS: There were 70 patients with a mean age of 61.6±9.9 years in Group 1 and 210 patients with a mean age of 62.7±9.8 years in Group 2. As a result of the analysis, it was found that the presence of concomitant chronic obstructive pulmonary disease, concomitant diabetes mellitus, blood and blood product transfusion, postoperative 2nd day C-reactive protein, postoperative 1st day neutrophil-to-lymphocyte ratio, and delta neutrophil-to-lymphocyte ratio was found as independent predictive factors of postoperative deep sternal wound infection development (p=0.043, p=0.012, p=0.029, p=0.009, p=0.002, and p<0.001; respectively). As a predictor of deep sternal wound infections development, postoperative 1st day neutrophil-to-lymphocyte ratio cutoff value was 11.2 (area under the curve [AUC] 0.598; p=0.014; 60% sensitivity, and 65.2% specificity), and delta neutrophil-to-lymphocyte ratio cutoff value was 9.6 (AUC 0.716; p<0.001; 57.1% sensitivity, and 73.8% specificity). CONCLUSIONS: Deep sternal wound infection development can be predicted with inflammatory parameters such as neutrophil-to-lymphocyte ratio and C-reactive protein that are obtained from cheap and easily available routine biochemical tests.