Drug coverage decisions require information about clinically relevant benefits and risks, as well as economic information about direct and indirect costs, in comparison with relevant treatment alternatives. A recent Canadian initiative aims to improve the evidentiary basis for drug coverage decisions through centralised evaluation of the clinical and economic value of new drug products. Centralised review can make important, 'positive' contributions to decision making by raising the evidentiary basis for decisions. Even in the absence of a single-payer for medicines, such information can directly inform decisions focussed on matters of technical efficiency. Centralised review also provides necessary but not sufficient information for the many decisions in this sector that concern allocative efficiency and therefore have 'normative' implications. Thus, in addition to processes for collecting and critically assessing clinical and economic data, effective priority setting requires processes at a local level for engaging affected populations in the consideration of the trade-offs inherent in coverage decisions.