OBJECTIVES: Geographic transferability of model-based cost-effectiveness results across countries can facilitate and shorten the appraisal process for reimbursement of pharmaceuticals. The objective of this study was to assess the transferability of a UK model-based cost-effectiveness analysis of trastuzumab in early breast cancer in order to obtain a Dutch cost-effectiveness estimate. METHODS: Three checklists published by  Welte et al (2004), Boulenger et al. (2005) and Urdahl et al. (2006) were used to assess the transferability of a UK model-based study to the Dutch setting. RESULTS: The UK study meets the general knock-out criteria from Welte et al, indicating that in the Netherlands, trastuzumab in early breast cancer is licensed and used in the same regimen as in the UK model. Applying the checklist by Boulenger et al produced a high transferability information score of 93%, indicating an adequate description of model inputs and transferability to the Dutch setting. The questions by Urdahl et al. could be answered adequately. The decision was made to adjust the health state utilities and  background mortality. All UK-prices on resource use were replaced by Dutch unit prices and updated to 2006. The friction cost method was used to calculate the costs of productivity loss. The cost inputs and the risk of cardiac adverse events were varied in one-way sensitivity analyses. CONCLUSIONS: Overall, transferring the UK-model structure and adjusting some of the model inputs to the Dutch setting proved to be an efficient method to obtain a reliable Dutch estimate for the adjuvant treatment of trastuzumab. The necessary adjustments were made to the cost-effectiveness study. Cost-effectiveness calculations, probabilistic sensitivity analysis, subgroup analyses, one-way sensitivity analysis and value of information analysis were performed. The outcomes of the modelling are adressed in a separate abstract.