It has often been proposed to restrict access to postmortal organs to registered donors, or at least to give them priority on the waiting list. Such proposals are motivated by considerations of fairness: everyone benefits from the existence of a pool of available organs and of an organised system of distributing them and it is unfair that people who are prepared to contribute to this public good are duped by people who are not. This paper spells out this rationale and (...) goes on to discuss the main principled objections that have been brought forward to such proposals. The most fundamental objection is that healthcare resources should be allocated in accordance with need, not with merit. The reply to this objection is that the principle of allocation according to need only holds in cases in which the provision of such resources and the fair distribution of the burdens of contribution are independently secured, as they are in an obligatory insurance system. (shrink)