Abstract: The Internet is rapidly becoming the most important mass medium in the 21stcentury. In a recent systematic review we have identified more than 30 papers which evaluate the quality of health information for consumers on the Internet (Eysenbach & Sa, in preparation). Almost all authors come to the conclusion that the majority of information on the Internet is poor and not evidence-based. On the other hand, the Internet has clearly the potential to act as a catalyst for evidence-based medicine, not only because it provides an infrastructure for health professionals to access resources and databases and helps systematic reviewers to identify unpublished evidence (Eysenbach et al., submitted), but also because it allows consumers to draw from the same knowledge base, thereby increasing consumer involvement in healthcare decision making and increasing the pressure on caregivers to deliver high quality health services.[1] But to achieve this, evidence-based information should be recognizable as such and identifiable for consumers on the web. In a recently launched project named medCERTAIN (medPICS Certification and Rating of Trustworthy and Assessed Health Information on the Net), supported by the European Union under the "EU Action Plan for Safer Use of the Internet", health information on the web will be "labeled" with meta-information. A technical and organisational infrastructure will allow associations (e.g. medical societies) and individuals (e.g. medical domain experts) to rate (i.e. to assign metadata to) health information on the Net, in a distributed, decentralised way, to allow consumers to put greater trust into reliable, evidence-based health information on the Net. Consumers will be able to use their browsers, or additional software or search engines to retrieve this metainformation automatically in the background whenever they access a website . Similarly, health kiosks (publicly accessible Internet terminals for use in libraries and hospitals) will use this infrastructure to limit access to quality assessed content on the web, or to display disclaimers if the consumer is leaving the "evidence-based" (rated) subset of the web. A "Collaboration for Critical Appraisal of Internet Health Information", proposed already in 1997 [2,3] is currently being formed, which brings together organisations and individuals who are active in the field of reviewing, appraising, rating, evaluating health information on the web, based on the consensus criteria, and to further develop methods and to exchange data. Together with the Cochrane Collaboration, this initiative hopes to improve dissemination of evidence to consumers on the Internet and thereby to advance evidence-based decision making in health care in empowering consumers to make informed, evidence-based decisions. 1. Eysenbach G, Sa ER, Diepgen TL. Shopping around the internet today and tomorrow: towards the millennium of cybermedicine. BMJ 1999;319:1294 [full] 2. Eysenbach G, Diepgen TL. Labeling and filtering of medical information on the Internet. Methods Inf.Med. 1999;38:80-88. 3. Eysenbach G, Diepgen TL. Towards quality management of medical information on the internet: evaluation, labelling, and filtering of information. BMJ. 1998;317:1496-1500