Medication reconciliation can help prevent adverse health outcomes, but the process is nontrivial. Here we focus on the user interface that clinicians might use to compare and merge two separate lists of medications. Similarities and differences between the lists need to be identified; decisions need to be made as to which medications should be continued and which ones should be stopped. We offer a novel prototype called Twinlist that uses animation and spatial layout to reveal similarities, and simple interactive controls to facilitate "accept" or "reject" decisions. See video: http://www.youtube.com/watch?v=YXkq9hQppOw