Health Technology Assessment OBJECTIVE: Since 1992, pharmacoeconomic guidelines, which contain specific costing recommendations, have been available yet reviews of recent economic evaluations indicate that investigators are still using a wide range of methods. This discourages uniformity of results. Two possible reasons for this are 1) insufficient detail in the recommended guidelines and 2) a lack of standardization. We conducted a comparative review of national costing guidelines to determine the degree of detail provided in the guidelines and the degree of correspondence. The main purpose was to develop a more comprehensive framework. METHODS: Guidelines were identified and reviewed. A framework with categories were developed, and all guidelines were reviewed in light of these categories. RESULTS: Our framework contained the following headings: General items, Resource identification and classification, Resource measurement, Resource Valuation, and reporting cost per patient. Our review of guidelines indicated that major differences arose because of different study purposes (studies conducted for formal formulary submissions versus general purpose studies). Other differences between the stated guidelines resulted from analytical differences in costing analysis, in areas such as lifetime unrelated costs and lost productivity costs. We also found an absence of detail in the costing recommendations. CONCLUSIONS: Both with regard to resource measurement and resource valuation categories, very little conceptual guidance relating to the basic cost measure was provided, and no systematic recommendations emerged with regard to inter-temporal and geographical adjustments to the basic cost measure. A more detailed set of recommendations is proposed.