To evaluate the effectiveness and safety of weekly docetaxel/carboplatin as primary systemic therapy (PST) for locally advanced breast cancer, we conducted a phase II study. Forty-four patients with HER2-negative locally advanced or inflammatory breast cancer (IBC) received docetaxel 35 mg/m(2) and carboplatin to an area under the curve of 2 mg/mL/min for 3 of 4 weeks over 16 weeks. After completion of PST, patients had breast surgery and then received 4 cycles of adjuvant cyclophosphamide/doxorubicin, standard radiation therapy, and, for hormone receptorpositive tumors, tamoxifen. The mean tumor size was 9.3 cm (range, 5-24 cm). Thirty-seven patients (85%) had palpable lymph nodes; 13 patients (30%) had matted or fixed nodes (N2). Eight patients had IBC. There were 11 clinical complete responses (25%) and 29 clinical partial responses (66%), resulting in 40 objective responses (91% [95% CI, 78%-96%]). Invasive disease disappeared (pathologic complete response) from the breast and axilla in 6 patients (14% [95% CI, 5%-27%]) and from the axilla in 17 patients (39% [95% CI, 24%-55%]). The only significant adverse hematologic event was grade 3 neutropenia in 4 patients (9%). The most common adverse nonhematologic events were fatigue (84% of patients) and alopecia (84%), which were usually grade 1/2. Weekly docetaxel/carboplatin appears to be active and feasible as PST in patients with large breast tumors.