Background: Key features examinations (KFEs) have been used to assess clinical decision making in medical education, yet there are no reports of an online KFE-based on a national curriculum for the internal medicine clerkship.What we did: The authors developed and pilot tested an electronic KFE based on the US Clerkship Directors in Internal Medicine core curriculum. Teams, with expert oversight and peer review, developed key features (KFs) and cases.Evaluation: The exam was pilot tested at eight medical schools with 162 third and fourth year medical students, of whom 96 (59.3%) responded to a survey. While most students reported that the exam was more difficult than a multiple choice question exam, 61 (83.3%) students agreed that it reflected problems seen in clinical practice and 51 (69.9%) students reported that it more accurately assessed the ability to make clinical decisions.Conclusions: The development of an electronic KFs exam is a time-intensive process. A team approach offers built-in peer review and accountability. Students, although not familiar with this format in the US, recognized it as authentically assessing clinical decision-making for problems commonly seen in the clerkship.