The objective of this pilot study was to explore the applicability of various evaluation methods (subjective and objective) for assessing usability of electronic health record system (EHRs) during physician interaction on simple vs. complex tasks. Five physicians performed two simulated clinical scenarios consisting of 9 tasks using the EHR. Tasks were categorized into simple vs. complex tasks based on the user, task and context characteristics by the subject matter expert. Usability was assessed using four methods, (1) subjectively using subject's informal feedback and usability expert's heuristics, (2) workload measures using eye tracking, (3) behavior measures using clicks and navigation windows, and (4) performance measures using actual time on task and predictive time based on CogTool ©. Overall, the results suggest that heuristic methods (1) are highly effective in identifying usability issues, with other methods (2-4) providing complementary analysis to identify differences is task complexly and user experience with EHRs.