Breast conservation therapy is an accepted treatment option for early stage breast carcinoma, but is rarely considered appropriate for locally advanced nonmetastatic lesions. Mastectomy specimens of 46/50 patients treated at the Ochsner Clinic and the Mallinckrodt Institute of Radiology with neoadjuvant chemotherapy prior to mastectomy +/- irradiation were evaluated by a single pathologist to assess tumor response to chemotherapy. Forty percent of this group would potentially have been eligible for breast conservation therapy, using a residual tumor size of < or = 4 cm with negative surgical margins as the criteria. Patients most likely to qualify for breast conservation therapy were those with T3N0-1 lesions (67%). Least likely were patients with skin involvement at diagnosis 4/33 (12%). Tumors with an extensive intraductal component at biopsy often had residual islands of intraductal carcinoma occupying the original tumor volume, even when the invasive component was absent or much reduced. A prospective trial will be required to determine whether or not acceptable local control rates can be obtained after breast conservation therapy for that subset of patients with a favorable response to induction chemotherapy.