11517 Background: We analyses a mono institutional series of patients treated with metastatic breast cancer (MBC). Methods: From 2000 to 2006 forty consecutive patients affected by MBC were evaluated. The average age was 50 years (range: 30–79). All patients had HER2+ tumors (IHC 3+ or FISH+) and LVEF > 50%. Metastatic sites were: liver 18, lymph nodes 10, bone 9, skin 7, lung 5 pts. In 11 cases the sites of metastases were multiple (1–3). All patients were treated with Trastuzumab 4 mg/kg loading dose and 2 mg/kg weekly thereafter with weekly Paclitaxel 80 mg/m2 or weekly Vinorelbine 25 mg/m2; specifically, Paclitaxel was used in 26 patients and Vinorelbine in 14 patients. The endpoints were time to progression (TTP), duration of response, toxicity (including cardiologic) and overall survival. Results: A total of 1271 courses of weekly Trastuzumab were administered (average 28 courses per patient: range 8–72). There were 22 complete and partial responses (CR+PR=55%). In the association of Trastuzumab and Paclitaxel were seen :11 CR, 6 PR, 3 SD and 6 PD, (RR 65.3%). In the combination of Trastuzumab and Vinorelbine: 2 CR, 3 PR, 4 SD and 5 PD (RR 35.7%) . The most responsive sites were: liver 15 CR+PR (37.5%), lung 11 CR+PR (27.5%), lymph nodes 8 CR+PR (20%), and skin 6 CR+PR (15%). TTP was 7 months (2–27 months) and response duration 6.7 months (2–26 months). Overall survival at 5 years was estimated at 26.4 months. Toxicity rates were: hematological grade 4 in 2 pts, grade 3 in 3 pts, neurological grade 3 in 19 pts. No important cardiologic toxicity was observed: LVEF was reduced to 40% in 4 pts. Seven patients developed brain metastasis during therapy. The patients in PD continued Trastuzumab with other chemotherapy, no responses were observed. The median cost of treatment with Trastuzumab for patient was 16.147 € (range 3.987–39.959 €. Conclusions: Treatment with Trastuzumab plus chemotherapy has been shown to be effective and well-tolerated providing a good quality of life. The economic impact is important and is to define. The cost/benefit in this cohort of the patients is ongoing. No significant financial relationships to disclose.