Optimal postoperative pain management is required to improve the quality of life of patients after modified radical mastectomy (MRM). PECS II block and local infiltration anesthesia (LIA) are multimodal analgesia modalities that can be used in MRM patients. Neutrophil-lymphocyte ratio (NLR) is an affordable, widely available marker, and has been shown to be useful in assessing therapeutic response. This study compared PECS II block with ALI on postoperative NLR and pain intensity in MRM patients. METHODSː This study used a single-blind randomized trial design. The subjects were divided into group 1 (PECS II block) and group 2 (LIA). Neutrophil-lymphocyte ratio were examined 1 hour preoperatively (T0), 2 hours (T1) and 12 hours (T2) postoperatively in both groups. Pain intensity was assessed at 0 (T0), 2 (T1), 4 (T2), 6 (T3), 12 (T4), and 24 (T5) hours postoperatively using the Numeric Rating Scale (NRS). RESULTSː The NLR was higher in group 2 at T2 and T0 T2 (p=0.015 and p=0.013). The resting NRS was higher in group 2 at T4 (p=0.009) and T0-T4 (p=0.046). Total fentanyl requirement in 24 hours was higher in group 2 (p=0.011). CONCLUSIONSː PECS II block can be used as one of the multimodal analgesia regimens for postoperative pain management of MRM patients, and LIA can be an alternative option in conditions where no ultrasound modality is available.