[Results registries for clinical trials--a milestone on the way to transparency in clinical research?]

Publication bias, i.e., the publication of trial results depending on the nature and direction of results, is a significant problem in healthcare, as it leads to a biased view of the treatment options available. Furthermore, publication bias hampers the adequate planning and conduct of future clinical trials. One proposal to reduce publication bias is the registration of trials and trial results. Whereas the registration of trials at inception is largely accepted and partly established, the registration of trial results is still being intensively discussed. Open issues particularly refer to legal obligations in the registration of trial results as well as to the nature and extent of their presentation. Whilst in the United States a comprehensive legal regulation on results registration has already been implemented, compulsory registration in Europe is still at a preliminary stage. The present paper describes the status quo of results registries, discusses registration requirements, and outlines the need to develop methods for the handling of results registries.