Lymph node metastasis is often the first indication of the aggressiveness of breast cancer. Effective chemotherapy in breast cancer depends on targeting the metastatic component of the disease. In order to optimize chemotherapy in the metastatic target of breast cancer, the histoculture drug response assay (HDRA) was performed on surgical specimens of primary tumor and axillary lymph node metastasis from 30 breast cancer patients. The surgical specimens were cut into approximately 10 mg pieces, and placed onto the collagen gel sponges in the medium containing previously-determined cutoff concentrations of doxorubicin (DXR), 5-fluorouracil (5-FU), cisplatin (DDP), and mitomycin C (MMC). After incubation for 7 days, the chemosensitivity of the tumor fragments was evaluated with the 3-(4,5-dimethythiazol2yl)-2,5-diphenyl-2H tetrazolium bromide (MTT) endpoint. The lymph node metastases were more resistant than the primary tumor for DXR, 5-FU, and MMC (p < 0.05) but not for CDDP. The data suggest that both primary tumor and metastases from individual patients should be tested in the HDRA to enhance clinical efficacy of chemotherapy.