Twenty-one cancers in 20 patients with locally advanced breast cancer were studied. Incisional biopsy was performed without using electrocautery. Tissue was obtained for histology and estrogen (ER) and progesterone (PR) receptors. Patients received chemotherapy after biopsy. All responded and had radical mastectomy performed. Tissue was removed from the mastectomy specimen to confirm residual tumor and for repeat receptor measurements. Initial receptor levels were negative in 13 cancers. Following chemotherapy, both ER and PR levels were unchanged in 11 cancers. Levels in one cancer changed from ER-PR- to ER+PR- and one changed from ER-PR- to ER+PR+. Six cancers were ER+PR+ at initial examination. Repeat receptor levels after chemotherapy were ER+PR+ in three. One ER+PR+ tumor became ER-PR+, one changed to ER+PR-, and one to ER-PR-. One ER+PR- cancer remained ER+PR- after treatment and an ER-PR+ cancer became ER-PR- after treatment. Chemotherapy dose not significantly alter hormonal levels in breast cancer tissue.