The purpose of this study was to assess the efficacy and predictive biomarkers of combination docetaxel-trastuzumab in a neoadjuvant setting by means of a phase II trial. Women with histologically-confirmed advanced invasive breast cancer whose tumours overexpressed HER-2 received 4 cycles of docetaxel (70 mg/m2 every 3 weeks) and trastuzumab (4 mg/kg loading dose, 2 mg/kg weekly thereafter). Twenty-one patients were enrolled, and all completed 4 cycles of treatment. Two patients were later found to be inoperable, and neither pathological nor clinical response was assessed. The pathological complete response rate was 21% (4/19; 95% CI, 6-46%) and the overall clinical response rate 89% (17/19; 95% CI, 67-99%). The relationship between the expression of biomarkers (HER-2, c-MYC, BRCA1 and Ki-67) and pathological response was assessed. The results suggested the possibility that tumours showing a high signal ratio of HER-2/CEP17 or c-MYC/CEP17 might be more sensitive to this combination therapy. Based on these results, it can be speculated that approximately 30% pCR might be obtained in cases with a high signal ratio of HER2/CEP17 or c-MYC/CEP17. Further trials are needed.