Objective To investigate the correlation of body mass index (BMI) on pathological complete response (pCR) and prognosis of breast cancer patients receiving neoadjuvant chemotherapy.Methods A retrospective analysis was performed on 98 cases of breast cancer patients in the Tumor Hospital Affiliated to Zhengzhou University from December 2013 to November 2015.Patients were divided into normal or underweight (N/U,BMI ＜25.0 kg/m2) group,overweight (OW,BMI 25.0-29.9 kg/m2)group and obese (OB,BMI ≥30.0 kg/m2) group according to BMI.A total number of 50 (51.0％) patients were N/U,32 (32.6％) patients were OW,and 16 (16.3％) patients were OB.The pathological complete remission after neoadjuvant chemotherapy was observed,and the prognostic evaluation index was disease-free survival rates.Univariate analysis of BMI and pCR correlations was performed by Chi-square test or Fisher exact test,and logistic regression for multivariate analysis.Kaplan-Meier analysis and log-rank test were used to analyze survival status,and Cox proportional hazard model analysis for multivariate analysis.Results In this study,A statistically significant difference was found in the molecular subtypes of the three groups(P ＜ 0.05).Twenty-nine(29.6％) patients achieved pCR,pCR rates in N/U group,OW group and OB group were 36.0％ (18/50),25.0％ (8/32),and 18.8％ (3/16),respectively,but the difference was not statistically significant (P ＞ 0.05).Multivariate logistic regression analysis showed that obesity and molecular subtype were independent factors of pCR in all patients (P ＜ 0.05).The 3-year disease free survival rates of the N/U,OW,and OB groups were 84.0％,93.5％ and 80.4％,respectively (P ＞ 0.05).Multivariate survival analysis showed that the BMI was not an independent prognostic factor for the 3-year disease free survival rate (P ＞ 0.05).Conclusion Excessive BMI (obesity) is an independent predictor of pCR in breast cancer patients receiving neoadjuvant chemotherapy,but does not affect the prognosis of these patients.