Background: The Techniker Krankenkasse (TK), a German statutory health insurance fund, has developed a web-based interactive patient information (‘patient dialogue’) in cooperation with the Section of Clinical Epidemiology and Health Services Research at the University Medical Center Freiburg. It is based on the concept of shared decision making and addresses insurers who are facing a medical decision. In addition to a generic module for patient competencies for participating in decision making with their physician, it includes modules for depression and acute low back pain with a focus on evidence-based treatment options. Objectives: ‘Patient dialogue’ aims at the advancement of patient competencies for participating in medical decisions and at the improvement of patients’ information and acceptance towards evidence-based treatment. Methods: The system is currently being evaluated within a randomized controlled trial with N = 500 patients. Primary outcomes are decisional conflict and knowledge. Further outcomes include preparation for decision making, participation in decision making, and satisfaction with treatment. Users in the intervention group receive access to patient dialogue while participants in the control group use a static patient information. The online evaluation takes place prior to and right after system use as well as three months later. Results: Since the launch of patient dialogue N = 302 participants have taken part in the evaluation. First results on the general satisfaction with the system indicate that it is very well understandable for 85% of the users. Results of the randomized trial regarding the outcomes decisional conflict, knowledge and preparation for decision making will be available in April 2008. Conclusions: It is expected that an individually tailored patient information such as ‘patient dialogue’ fosters patient participation in decision making and leads to decisions that are concordant with patients’ preferences.