NSABP B-18 randomized women with operable breast cancer to receive chemotherapy either pre- or postoperatively; OS and DSF rates at 9 years were identical. Importantly, pathologic complete response (pCR) was directly proportional to DFS and OS. Recently, dose dense adjuvant chemotherapy has shown a statistically significant improvement in DFS and OS. However, no data is available for the use of dose dense preoperative chemotherapy at this time. Methods: Women enrolled in the I-SPY correlative trial with newly diagnosed breast cancer, T ≥ 3cm, any N, M0 were evaluated to assess response rates and safety to dose dense neoadjuvant chemotherapy (doxorubicin 60 mg/m2 IV Q2 wks × 4, paclitaxel 175 mg/m2 IV Q2 wks × 4, and cyclophosphamide 600 mg/m2 IV Q2 wks × 4). Results: Since 02/2003, 43 pts have been treated with dose dense neoadjuvant chemotherapy on the I-SPY trial at UAB (mean age 47.9). 47% of the pts were ER+, 37% were PR+ and 5% were Her2+ by FISH. 2 pts dropped out for personal reasons and 9 pts are actively undergoing treatment. Overall, 32 pts received dose dense chemotherapy and proceeded to surgery. Of those, 31 received dose dense sequential ATC and 1 received dose dense concurrent AC followed by T. 34% had a pCR (breast & nodes) while an additional 10% had a pCR in the breast but residual disease in lymph nodes; 41% had a PR; 9% had SD; and 6% had PD. Hematologic toxicity consisted of grade 3 anemia in 2 pts, febrile neutropenia in 2 pts and no grade 4 thrombocytopenia. Non-hematologic grade 3–4 toxicity consisted of mediport-associated thrombosis in 2 pts, hyperglycemia in 2 pts, syncope in 1 pt, neuropathy in 1 pt, and disseminated varicella in 1 pt. Conclusion: Our results show that dose dense neoadjuvant chemotherapy achieves a pCR (breast & nodes) in about 1/3 of patients (34%) with tolerable toxicity.