 This single arm study will assess the efficacy and safety of Avastin in combination with Herceptin and Xeloda as first-line treatment of patients with HER2-positive locally recurrent or metastatic breast cancer. Patients will receive 3-weekly treatment cycles of Herceptin 8mgkg iv on day 1 of first cycle, followed by 6mgkg iv maintenance dose on day 1 of subsequent cycles, Xeloda 1000mgm2 bid po on days 1-14 of each treatment cycle and Avastin 15mgkg on day 2 of first treatment cycle,and on day 1 of each subsequent cycle.The anticipated time on study treatment is until disease progression, and the target sample size is 100 individuals. 