Organs available for transplantation are scarce and valuable medical resources and decisions about who is to receive them should not be made more difficult by complicated calculations of desert. Consideration of likely clinical outcome must always take priority when allocating such a precious resource otherwise there is a danger of wasting that resource. However, desert may be a relevant concern in decision-making where the clinical risk is identical between two or more potential recipients of organs. Unlikely as this scenario is, such a decision procedure makes clear the interdependence of organ recipient and organ donor and hints at potential disadvantages for those who are willing to accept but unwilling to donate organs (free-riders). A combined opting-out and preference system weakens many of the objections to opting-out systems and may make the decision to donate organs on behalf of their deceased relatives easier for families. (Journal of Medical Ethics 1998;24:166-170)