Pathologic complete response (pCR) is linked to a better outcome, but its definition varies among working groups. We performed this study to validate different expressions of pCR as well as to determine the role of in situ and isolated tumor cell residues. A pathologic review was conducted on 710 operable patients with breast cancer to assess the residual disease in breast and in nodes according to the Chevallier (Ch) and Sataloff's (Sa) classifications. The pCR rate was 14.3% according to the Chevallier and 25.8% according to the Sataloff's classification. Overall survival and disease-free survival have been compared according to the pathologic response. There were significant differences between the pCR Ch(1+2) or Sa(A) and the non-pCR group. No significant difference was found between classes Ch(1) versus Ch(2) and between class Sa(A) without isolated cells versus class Sa(A) with isolated cells. Conversely, tumors histologically modified by chemotherapy were associated with a better prognosis than unmodified tumors. Finally, evidence of pCR in nodes was associated with a better prognosis. pCR should be defined as an absence of node invasion, and in the breast, either absence of tumor or tumor residue less than 5% of the tumor.