<h3>Purpose/Objective(s)</h3> To investigate the prognostic value of tumor-infiltrating lymphocytes (TIL) in patients with triple-negative breast cancer (TNBC). <h3>Materials/Methods</h3> The clinicopathologic data of 258 patients with I-III stage TNBC treated in one institution from 2010 to 2013 were collected. Two-hundred and twelve patients (82.2%) received mastectomy and 46 (17.8%) received breast-conserving surgery. Eighty-four patients (32.6%) had stage I, 138 (53.5%) had stage II and 36 (14.0%) had stage III disease. All had received adjuvant chemotherapy without neoadjuvant therapy, and 96 (37.2%) received postoperative radiotherapy. The density of TILs with its expression of stromal (s) and intratumoral (i) CD8, FOXP3 (sCD8, iCD8, sFOXP3, iFOXP3) were evaluated by hematoxylin and eosin and immunohistochemical (IHC) staining. An IHC staining for PD-1 and PD-L1 (22C3) were also conducted. Locoregional recurrence (LRR), distant metastasis (DM) and disease-free survival (DFS) and overall survival (OS) rates were calculated by using the Kaplan-Meier method and compared by log-rank test. The association of relapse and survival outcomes with TILs concentration was evaluated using multivariable proportional hazards regression. Optimum cutoff values for sCD8, iCD8, sFOXP3 and iFOXP3 were identified using the maxstat package in R. <h3>Results</h3> At a median follow-up of 80 months (range, 9-111 months), patients with lymphocyte-predominant breast cancer (sTIL ≥60%) had significantly lower 5-year LRR (3.6% vs 15.6%; <i>P</i> = 0.047) and higher DFS (96.4% vs 84.5%; <i>P</i> = 0.025) compared to those with < 60% sTIL. Patients with sCD8 > 10% had significantly lower 5-year LRR (4.2% vs 15.7%, <i>P</i> = 0.010) and DM (2.8% vs 14.6%; <i>P</i> = 006) and higher 5-year DFS (95.8% vs 83.9%, <i>P</i> = 0.015) and OS (97.1% vs 91.2%, <i>P</i> = 0.044) compared to patients with sCD8 ≤10%. Patients with iCD8 > 5% had significantly lower 5-year LRR (2.2% vs 14.8%, <i>P</i> = 0.013) and DM (13.4%, <i>P</i> = 0.021) and higher 5-year DFS (97.8% vs 84.8%, <i>P</i> = 0.008) and OS (97.7 vs 91.7%, <i>P</i> = 0.030) compared to patients with iCD8 ≤5%. Patients with sFOXP3 > 3/HPF also had significantly lower 5-year LRR (4.5% vs 15.0%, <i>P</i> = 0.012) and DM (5.9% vs 13.5%, <i>P</i> = 0.043) and higher 5-year DFS (92.7% vs 85.0%, <i>P</i> = 0.034) and OS (95.6% vs 91.5%, <i>P</i> = 0.047) compared to sFOXP3 ≤3/HPF. However, no survival benefits were found from patients with iFOXP3 > 14/HPF. Presence of PD-1-positive immune cells in TNBC were associated with a significantly better DFS (93.4% vs 83.5%, <i>P</i> = 0.044), while PD-L1 expression had no impact on patient outcomes. Multivariate analysis revealed that sTIL ≥60% (HR 0.23, 95% CI 0.05-0.99, <i>P</i> = 0.048) or PD-1 positivity (HR 0.40, 95% CI: 0.16-0.96, <i>P</i> = 0.041) were independent prognostic factors for DFS, in addition to stage (<i>P</i> < 0.001). No other subsets of TILs nor PD-L1 was independently associated with relapse or survival (all <i>P</i> > 0.05). <h3>Conclusion</h3> High density of stromal TIL and presence of PD-1-positive immune cells may have a positive prognostic value in TNBC. These findings need further validation.