This article is part of a For-Discussion-Section of Methods of Information in Medicine about the paper “Evidence-based Health Informatics: How Do We Know What We Know?” written by Elske Ammenwerth . It is introduced by an editorial. This article contains the combined commentaries invited to indepen dently comment on the Ammenwerth paper. In subsequent issues the discussion can continue through letters to the editor. With these comments on the paper “Evidence-based Health Informatics: How do we know what we know?”, written by Elske Ammenwerth , the journal seeks to stimulate a broad discussion on the challenges of evaluating information processing and information technology in health care. An international group of experts has been invited by the editor of Methods to comment on this paper. Each of the invited commentaries forms one section of this paper.