OBJECTIVES: Based on results from the HERceptin Adjuvant Trial (HERA) with a median follow-up time of 1 year, trastuzumab is licensed and reimbursed for the treatment of HER2+ early breast cancer (EBC) in Italy since 2006. As the risk of recurrence reduces overtime, hazard ratios in breast cancer trials usually increase as more follow-up data is available. Longer term follow-up data were recently reported for 2 and 4 years, the latter though being heavily confounded by extensive cross-over of the HERA comparator arm and hence unusable. The objective of this analysis was therefore to determine the cost effectiveness of 1-year treatment with trastuzumab vs observation, based on results from the 2-year follow up data. METHODS: A published Markov model based on the initial HERA results was revised and updated to incorporate the hazard ratios from the 2-year follow up data to reflect trastuzumab’s impact on disease progression. The treatment effect reported was applied for the first 4 years of the model.  An Italian health care payer perspective was adopted. Medication and acquisition costs were taken from published sources whereas health state and event costs were derived from costing study conducted in Tuscany. A lifetime horizon was chosen. Incremental cost-effectiveness ratios were expressed as cost per quality adjusted life year (QALY). Costs and QALYs were discounted at 3.0% p.a. Sensitivity analyses were performed. RESULTS: The analysis showed that after completion of adjuvant chemotherapy, treatment with trastuzumab resulted into additional 1.81 life years and 1.62 QALYS gained per patient compared to observation only, at an incremental mean total cost of €18,022. The ICER was estimated at €11,131/QALY, which is well in line with previously published analyses. CONCLUSIONS: Using more recent data from the HERA trial, Trastuzumab was determined to remain a cost effective treatment option for HER2+ve EBC in the Italian setting.