BACKGROUND: In the Netherlands, decisions about the reimbursement of new pharmaceuticals are based on cost effectiveness, as well as therapeutic value and budget impact. Since 1 January 2005, drug manufacturers are formally required to substantiate the cost effectiveness of drugs that have therapeutic added value in comparison with existing ones through pharmacoeconomic evaluations. Dutch guidelines for pharmacoeconomic research provide methods guidance, ensuring consistency in both the evidence and the decision-making process about drug reimbursement. AIM: This study reviewed the methodological quality of all 21 formally required pharmacoeconomic evaluations of new pharmaceuticals between 1 January 2005 and 1 October 2008, and verified whether these evaluations complied with pharmacoeconomic guidelines. METHODS: Data on the quality of the pharmacoeconomic evaluations were extracted from the pharmacoeconomic reports published by the Dutch Health Care Insurance Board (CVZ). The Board's newsletters provided information on the advice to, and reimbursement decisions made by, the Dutch Minister of Health. All data extraction was carried out by two independent reviewers, and descriptive analyses were conducted. RESULTS: The methodological quality was sound in only 8 of the 21 pharmacoeconomic evaluations. In most cases, the perspective of analysis, the comparator drugs, and the reporting of both total and incremental costs and effects were correct. However, drug indication, form (i.e. cost utility/cost effectiveness) and time horizon of the evaluations were frequently flawed. Moreover, the costs and effects of the pharmaceuticals were not always analysed correctly, and modelling studies were often non-transparent. Twelve drugs were reimbursed, and nine were not. CONCLUSIONS: The compliance with pharmacoeconomic guidelines in economic evaluations of new pharmaceuticals can be improved. This would improve the methodological quality of the pharmacoeconomic evaluations and ensure consistency in the evidence and the decision-making process for drug reimbursement in the Netherlands.