The efficacy and safety of combination therapy of 4 cycles with docetaxel 70 mg/m(2)every 3 weeks and trastuzumab as primary chemotherapy for operable breast cancer was determined in 21 patients (pts) by assessing the pathological complete response (pCR) rate, clinical response rate (RR), breast conservation surgery (BCS) rate and toxicities. To date, 19 pts have completed surgery. The pCR rate was 21% [95% CI 6%-46%] . The overall RR was 90% [95% CI 67%-99%] , with 5 CR, 12 PR, 2 SD and 0 PD. Grade 3 or 4 adverse events were leukopenia 48%, neutropenia 67%, hemoglobin 5%, and febrile neutropenia 10%. All non-hematological toxicities were mild and manageable. The pCR rate is not as low as that achieved in previous international studies. The combination of docetaxel and trastuzumab was a well-tolerated and very active regimen for the treatment of patients with HER 2-overexpressing operable breast cancer. This regimen promises to be one of the leading future treatments for progressive breast cancer.