Objective:To investigate the expressions of natural killer (NK) cells, interleukin-27 (IL-27) and CXC chemokine ligand 10 (CXCL10) in triple-negative breast cancer patients and non-triple-negative breast cancer patients and their clinical significances.Methods:Forty-eight cases of triple-negative breast cancer, 50 cases of non-triple-negative breast cancer and 50 cases of benign breast diseases diagnosed by pathology in the People's Hospital of Xinjiang Uygur Autonomous Region from January 2012 to June 2016 were selected. The expression of NK cells, IL-27 and CXCL10 in the paraffin sections of tissues of the patients after surgery were detected by immunohistochemistry, and the relationships between them and clinical features and prognosis of the patients were analyzed.Results:The positive expression rates of NK cells in triple-negative breast cancer, non-triple-negative breast cancer and benign breast diseases tissues were 81.25% (39/48), 64.00% (32/50) and 26.00% (13/50), respectively, and the difference was statistically significant ( χ2 = 28.229, P < 0.01); the positive expression rates of IL-27 in the three groups were 85.42% (41/48), 76.00% (35/50) and 16.00% (10/50), and the difference was statistically significant ( χ2 = 47.439, P < 0.01); the positive expression rates of CXCL10 in the three groups were 72.92% (35/48), 62.00% (31/50) and 18.00% (9/50), and the difference was statistically significant ( χ2 = 33.422, P < 0.01). In the triple-negative breast cancer group, the positive rate of NK cells was higher in patients with lymph node metastasis ( χ2 = 7.134, P = 0.008), the positive rate of IL-27 was higher in patients with tumor long-axis diameter > 2 cm ( P = 0.034), and the positive rate of CXCL10 was higher in patients with late tumor stage and lymph node metastasis ( χ2 = 8.574, P = 0.003; χ2 = 4.789, P = 0.049). In the non-triple-negative breast cancer group, the positive rate of IL-27 was higher in patients with tumor long-axis diameter > 2 cm ( χ2 = 6.711, P = 0.010), and the positive rate of CXCL10 was higher in patients with high tumor histological grade ( χ2 = 7.621, P = 0.006). The overall survival difference between NK cells-positive and NK cells-negative triple-negative breast cancer patients was statistically significant ( P = 0.047), and the prognosis of NK cells-positive patients was worse. Conclusions:The expressions of NK cells, IL-27 and CXCL10 are related to the occurrence and development of breast cancer. NK cells can be used as a potential prognostic indicator and a clinical treatment target for triple-negative breast cancer patients.