Aim: Breast cancer is one of the cancers with the highest morbidity and mortality in women. Surgical excision of axillary lymph nodes facilitates staging and provides regional control in those with axillary metastases. Although SLNB is routinely performed in the management of patients with cN0 disease who underwent primary surgery, it is controversial when to perform SLNB in patients receiving neoadjuvant chemotherapy. In our study, we evaluated the success of the platelet/ lymphocyte ratio before and after neoadjuvant therapy in predicting sentinel lymph node metastases in breast cancer patients receiving neoadjuvant therapy. Materials and Methods: Patients who received neoadjuvant chemotherapy for locally advanced breast cancer in our clinic were evaluated. Among these patients, patients with histopathologically proven axilla metastases but no pathological lymph nodes in clinical examination and imaging methods after neoadjuvant therapy were evaluated. Results: An average of 3.81 lymph node excisions were performed for sentinel lymph node sampling. We studied the PLR cut-off value with Roc-curve analysis. We found the cut-off value of 138.88 with a standard error of 0.061 (p=0.001). Patients with high PLR are more likely to have sentinel lymph node metastases than patients with low PLR (OR= 1.013, 95%Cl: 1.005-1.021, p=0.002). We also found a significant positive correlation between PLR and the number of metastatic sentinel lymph nodes (p=0.005). Each unit increase in PLR can cause an increase of 0.004 units in the number of metastatic sentinel lymph nodes. Conclusion: In patients receiving neoadjuvant chemotherapy, PLR plays an important role in predicting sentinel lymph node metastasis as a practical, simple, and inexpensive hematological indicator and may facilitate the selection of an appropriate treatment plan before surgery.