Background: Triple negative breast cancer (TNBC) is characterized rapid tumor growth, and increased metastatic potential compared to other breast cancer subtypes. However, pathological complete response (pCR) to neoadjuvant chemotherapy (NACT) can predict patients with a better prognosis. Clinical predictors of pCR such as tumor size (TS) are controversial. This study aims to evaluate the influence of TS on achieving pCR, and the associated survival outcomes. Methods: Medical records from 310 TNBC patients treated with NACT between 2010 and 2013 in National Cancer Institute Brazil were screened. The aim study was to examine the impact of TS on pCR. We used descriptive statistics to organize and summarize TS data and all the other variables of interest. Logistic regression has done to assess if any of these variables were associated with pCR. Survival data were extrapolated using Kaplan-Meier analysis and log-rank tests. Results: Thirty-nine (21%) of 187 enrolled patients achieved pCR. Median age was 48 years, 50.27% were postmenopausal, 93.03% T3/T4 and 75.39% axillar clinical node-positive; 92.51% received an anthracycline regimen followed by a taxane. Age >40 years (P=0.04, OR 0.45, 95% CI, 0.20-0.95) and tumor infiltrating lymphocytes (TILs) presence (P<0.01, OR 3.71, 95% CI, 1.60-8.60) were factors significantly associated with increased rates of pCR. Neither the TS (IQR: 4; P=0.22, OR 0.93, 95% CI, 0.83-1.03) nor the other subgroups analysed demonstrated any association with achieving pCR. Median follow-up was 36 months. The 5-year OS and RFS of the study population was 71.20% and 61.10% respectively. Conclusions: Preoperative TS did not significantly impact pCR rate in our cohort of patients receiving NACT for TNBC. Characteristics associated with higher pCR rate included TILs and age >40 years. In addition, pCR, was indicative of better survival outcomes.