Background: The 9th iteration of the American College of Chest Physicians antithrombotic therapy guidelines (AT9) is applying the Cochrane/GRADE system to assess the quality of evidence and move from evidence to recommendations. Guideline panellists use the evidence profiles – standardized tables that provide identical information to the Cochrane Summary of Findings tables with additional information regarding the rationale for quality of evidence judgments – to summarize the quality of evidence and estimated effects for important outcomes. Objective: To determine user preferences, understanding and time spent finding key information presented in two different formats of the GRADE evidence profiles. Study design and setting: Using email invitations and an online questionnaire (SurveyMonkey), we will invite 116 eligible AT9 panellists and randomize them to receive two formats of the evidence profile, one that approximates a currently recommended version (standard), and one with a number of important modifications (experimental). The modifications are: 1) placing explanatory information in the table instead of the footnotes; 2) eliminating observed event rates derived from included studies; 3) presenting calculated risk differences instead of raw absolute event rates; and 4) placing the relative effects in the table before the absolute effects rather than after them. We will create standard and experimental profiles for each of two clinical questions. We will measure user responses in terms of preferences, accessibility of information (easy to find, easy to use and helpful in making recommendation), correct comprehension and time needed to comprehend information in the evidence profile. Following completion of the initial part of the survey, respondents will review the alternative version and express their preferences between the two. Results and conclusion: We will conduct the study spring 2010 and present results at the Cochrane Colloquium. Results will inform formatting of evidence profiles and Summary of Findings tables for systematic reviews and practice guidelines.