Background: Web 2.0 internet tools and methods have attracted considerable attention as a means to improve health care delivery. Despite evidence demonstrating their use by medical professionals, there is no detailed research describing how Web 2.0 influences physicians' daily clinical practice. Hence this study examines Web 2.0 use by 35 junior physicians in clinical settings to further understand their impact on medical practice. Method: Diaries and interviews encompassing 177 days of internet use or 444 search incidents, analyzed via thematic analysis. Results: Results indicate that 53% of internet visits employed user-generated or Web 2.0 content, with Google and Wikipedia used by 80% and 70% of physicians, respectively. Despite awareness of information credibility risks with Web 2.0 content, it has a role in information seeking for both clinical decisions and medical education. This is enabled by the ability to cross check information and the diverse needs for background and non-verified information. Conclusion: Web 2.0 use represents a profound departure from previous learning and decision processes which were normally controlled by senior medical staff or medical schools. There is widespread concern with the risk of poor quality information with Web 2.0 use, and the manner in which physicians are using it suggest effective use derives from the mitigating actions by the individual physician. Three alternative policy options are identified to manage this risk and improve efficiency in Web 2.0's use.