Objective: To investigate the relations of CD8+ tumor-infiltrating lymphocytes (TILs) in breast cancer patients with their clinicopathologic features and survival outcomes. Methods: The CD8+ TILs expression in embedded tissue sections from 122 breast cancer patients was detected by immunohistochemical staining. According to the CD8+ TILs expression status, patients were divided into CD8+ TILs positive group and CD8+ TILs negative group, and the relations of CD8+ TILs with clinicopathologic features and survival outcomes were analyzed. Results: Among the specimens, the positive rate of CD8+ TILs expression was 32.14% (36/112). Statistical analysis showed that the differences in CD8+ TILs expression had statistical significance between or among the groups divided by degree of differentiation (χ2=6.277, P=0.043), TNM stage (χ2=3.963, P=0.047), and histological classification (χ2=4.299, P=0.038). The 5-year survival of CD8+ TILs positive group was significantly higher than that of CD8+ TILs negative group (88.89% vs. 71.05%, χ2=4.360, P=0.037). Log-rank test showed that the overall survival of CD8+ TILs positive group was significantly higher than that of CD8+ TILs negative group (P=0.043). Conclusion: CD8+ TILs can be used as a prognostic index for breast cancer patients and low infiltration of CD8+ TILs in tumor tissue may predict a poor outcome.