To explore the correlation between the peripheral blood neutrophil-to-lymphocyte ratio (NLR) and tumor infiltrating lymphocyte (TIL) before neoadjuvant therapy (NAT) and the prognosis of patients with triple negative breast cancer.A total of 126 patients with TNBC who received NAT were screened out. TILs, CD8+TIL and FOXP3+TIL were detected by immunohistochemistry in core needle biopsy specimens before treatment, and NLR was calculated. Kaplan-Meier analysis was used to estimate survival rates. Univariate and multivariate analyses were performed using Cox proportional hazards regression.NLR was negatively correlated with TILs density (p = 0.040) and FOXP3+ TIL was positively correlated with NLR (p = 0.019). Patients with low NLR/high TILs density showed the highest pCR rate (46/48, 95 %), while only 6/22 patients (21 %) with high NLR/low TILs density achieved pCR. Multivariate analysis showed that high NLR was independently associated with pCR ((HR = 5.043, 95 %CI = 1.637-15.535, p = 0.005). High T stage, lymph node involvement, lymphovascular invasion, high NLR, low TILs density and low CD8+ TIL were associated with poor OS and BCSS. Multivariate Cox regression analysis showed that high NLR (HR = 36.182, 95 %CI = 4.120-317.759, p = 0.001), high CD8+ TIL density (HR = 0.182, 95 %CI = 0.044-0.754, p = 0.019) were independently associated with poor OS. Similarly, high NLR (HR = 23.989, 95 %CI = 2.275-252.131, p = 0.008) was independently associated with worse BCSS.NLR may help to screen the high-risk population of TNBC patients after neoadjuvant therapy.Copyright © 2023 The Authors. Published by Elsevier GmbH.. All rights reserved.