Objective To evaluate the efficacy and safety of 1-year adjuvant trastuzumab (herceptin) versus 1-year non-trastuzumab observation in Chinese patients with HER2-positive early breast cancer during a median follow-up of 1 year.Methods The HERA trial was an international,multicenter,randomized,open-label,phase Ⅲ trial comparing treatment with trastuzumab for 1 and 2 years with observation after standard adjuvant chemotherapy,radiotherapy or both in patients with HER2-positive nodepositive or high-risk node-negative early breast cancer.The primary endpoint was disease-free survival.Secondary end points included recurrence-free survival,distant disease-free survival,overall survival and cardiac safety.The first planned interim analysis comparing the efficacy and safety of treatment with trastuzumab for 1 year versus observation were completed in April 2005.Only the outcomes of recruited Chinese patients were reported.Results A total of 122 Chinese patients from 8 participating centers were included for planned interim analysis.And they were divided into trastuzumab (n =68) and observation (n=54) groups.Three and eight disease-free survival events were observed in the trastuzumab and observation groups respectively.Two-year disease-free survival rates were 92.9％ and 81.4％ respectively (P =0.0489); 2-year recurrence-free survival and distant disease-free survivals were 98.1％ vs 81.4％ (P =0.0064) and 98.1％ vs 83.3％ (P =0.0117) respectively.Trastuzumab was generally well-tolerated with a decent safety profile.Severe cardiotoxicity was not observed.Conclusion One-year treatment with adjuvant trastuzumab improves disease-free survival,recurrence-free survival and distant disease-free survival in Chinese patients with HER2-positive early breast cancer.