Abstract: Objective:To evaluate the outcomes of women aged under35years with triple-negative (TN) breast cancer (BC) who underwent breast-conserving surgery (BCS).Methods:The medical records of 126 patients aged under 35years who underwent BCS in the Tianjin Medical University Cancer Institute and Hospital between January 2000and December 2009were retrospectively reviewed. On the basis of immunohistochemical methods, the patients were divided into TN and non-TN groups. The clinical features between the groups were compared to clarify the prognostic significance of TNBC. Results:The TN group was significantly associated with young age (P=0.029), early recurrence and metastasis (P=0.041), as well as high histological grade ( P=0.020). Five-year recurrence rates were 14.3% and 4.4% in the TN and non-TN groups, respectively (P=0.048). The distant metastasis rate between the two groups was 14.3% vs.12.1% (P=0.731), and the overall survival (OS) rate was 91.4% vs.95.6% (P= 0.349). Multivariate analysis was performed, and the recurrence rate was associated with histological grade (HR=10.686, P=0.019). TN was not the risk factor for local failure (HR= 3.469; P=0.064). The factors associated with OS were TNM stage (HR= 3.503, P=0.001) and histological grade (HR=5.472, P=0.020). Conclusion:The TN group exhibited earlier recurrence and metastasis, as well as higher recurrence rates, than those of the non-TN group. However, there were no significant differences in the distant metastasis rate and OS between TN and non-TN groups. Thus, TNBC should not be contraindicated for breast conservation.