BACKGROUND: There is an increasing number of health-care systems using economic evaluations to inform decisions about the reimbursement of health technologies. There are usually two separate elements of this process: assembling relevant evidence and undertaking analyses (technology assessment), and decision-making. In most systems, technology assessment is undertaken by the manufacturer of the technology. In a few, "third-party" assessment is used. METHODS: In the United Kingdom, the National Institute for Health and Clinical Excellence used a combination of third-party and manufacturer assessments between 1999 and 2005. After this point, a Single Technology Appraisal program (using manufacturer-based assessment) was instituted for some technologies. Here the role of third-party assessment is considered in this from of decision-making. The article reviews the requirements of economic evaluation to support decision-making, and considers the extent to which each type of assessment is likely to meet these requirements. It also attempts to address whether the two forms of assessment differ in their impact on decision-making using a comparison of the decisions made by National Institute for Health and Clinical Excellence (NICE) (under its multiple-technology appraisal system) and the Scottish Medicines Consortium (SMC), which relies on manufacturer assessment. RESULTS: The comparison is limited by the small number of technologies considered by both bodies. Nevertheless, it suggests that there are potentially important differences between the two bodies, with NICE generally placing more restrictions of the use of technologies. CONCLUSIONS: The article concludes that there are potential advantages to third-party assessment, but its cost and timing may preclude its use for all new technologies. A hybrid arrangement is suggested where third-party assessment is used in particular circumstances.