Objective To explore the correlation between serum levels of miR-193a-3p,activated transcription factor 5(ATF5),clinicopathological characteristics and chemotherapy efficacy in patients with triple negative breast cancer(TNBC).Methods A total of 120 patients with TNBC admitted to our hospital were collected as the research group.In the same period,120 cases with benign breast disease in our hospital were selected as the control group.Serum levels of miR-193a-3p and ATF5 were detected,and the relationship between them and clinicopathological characteristics were detected in two groups.According to the therapeutic effect,TNBC patients were divided into the treatment ineffective group(n=50)and the treatment effective group(n=70).The expression levels of miR-193a-3p and ATF5 were compared between the two groups,and factors affecting the chemotherapy efficacy of TNBC patients were analyzed.Results Compared with before chemotherapy,the serum miR-193a-3p level increased and ATF5 level decreased in TNBC patients after chemotherapy(P＜0.05).Compared with the control group,the serum miR-193a-3p level of TNBC patients decreased in the research group before chemotherapy,and ATF5 level increased(P＜0.05).The expression level of miR-193a-3p was lower and the expression level of ATF5 was higher in patients with tumor diameter≥3 cm,lymph node metastasis,low histological grade,clinical stage Ⅲ and Ki-67＞30%(P＜0.05).In TNBC patients,compared with the treatment effective group,patients in the treatment ineffective group showed a decreased serum miR-193a-3p level and an increased ATF5 level(P＜0.05).Lower level of miR-193a-3p,higher level of ATF5,lymph node metastasis,tumor diameter≥3 cm,low histological grade,and TNM stage Ⅲ were risk factors affecting the efficacy of chemotherapy in TNBC patients(P＜0.05).Conclusion Low level of miR-193a-3p and high level of ATF5 in the serum of TNBC patients are risk factors for chemotherapy efficacy.