[The definition of benefits: from the benefit package to the supply of services]

The definition of a "benefit package" of services covered by the National Health System of Spain--NHSS--raises technical and political problems. This article examines six relevant issues related with the implementation of this strategy: the instrument to define the services covered by the public system; health care expenditures; access to the services; quality; and the decision making-process. The definition of a comprehensive package of--broadly defined--services covered by the NHSS seems to be the most appropriate strategy, instead of a very detailed "catalog" of medical practices.