Objectives: To examine usability gaps among primary care resident physicians by clinical year: year 1(Y1), year 2(Y2), and year 3 (Y3) when using electronic health record (EHR). Methods: Twenty-nine usability tests with video analysis were conducted involving triangular method approach. Performance metrics of percent task success rate, time on task, and mouse activities were compared along with subtask analysis among the three physician groups. Results: Our findings showed comparable results for physicians of all three years in mean performance measures, specifically task success rate (Y1:95%, Y2:98%, Y3:95%). However, varying usability issues were identified among physicians from all three clinical years. Twenty-nine common usability issues across five themes emerged during sub task analysis: inconsistencies, user interface issues, structured data issues, ambiguous terminologies, and workarounds. Discussion and Conclusion: This study identified varying usability issues for users of the EHR with different experience level, which may be used to potentially increase physicians' performance when using an EHR. While three physician groups showed comparable performance metrics, these groups encountered numerous usability issues that should be addressed for effective EHR training and patient care.