BACKGROUND: The World Wide Web has led to the rapid growth of medical information and continuing medical educational offerings. Ease of access and availability at any time are advantages of the World Wide Web. Existing physician-education sites have often been designed and developed without systematic application of evidence and cognitive-educational theories; little rigorous evaluation has been conducted to determine which design factors are most effective in facilitating improvements in physician performance and patient-health outcomes that might occur as a result of physician participation in Web-based education. Theory and evidence-based Web design principles include the use of: needs assessment, multimodal strategies, interactivity, cl...