SummaryDespite widespread electronic health record (EHR) adoption, poor EHR system usability continues to be a significant barrier to effective system use for end users. One key to addressing usability problems is to employ user testing and user-centered design.To understand if redesigning an EHR-based navigation tool with clinician input improved user performance and satisfaction.A usability evaluation was conducted to compare two versions of a redesigned ambulatory navigator. Participants completed tasks for five patient cases using the navigators, while employing a think-aloud protocol. The tasks were based on Meaningful Use (MU) requirements.The version of navigator did not affect perceived workload, and time to complete tasks was longer in the redesigned navigator. A relatively small portion of navigator content was used to complete the MU-related tasks, though navigation patterns were highly variable across participants for both navigators. Preferences for EHR navigation structures appeared to be individualized.This study demonstrates the importance of EHR usability assessments to evaluate group and individual performance of different interfaces and preferences for each design.Citation: Hultman G, Marquard J, Arsoniadis E, Mink P, Rizvi R, Ramer T, Khairat S, Fickau K, Melton GB. Usability testing of two ambulatory EHR navigators.