Background: The mini-clinical evaluation exercise (mini-CEX) has been proposed as a method to address the deficiencies of in-training assessment for junior doctors. Aim: Our study aimed to determine the feasibility and value of adding mini-CEX assessments to the existing assessment processes for an intern cohort in the emergency department (ED). Methods: Interns undertook four mini-CEX assessments with senior ED medical officers, in addition to their standard in-training assessment processes. Assessment results and time taken to perform the mini-CEX assessments were recorded. Interns and assessors completed a survey regarding their perceptions of the mini-CEX assessment process. Results: The total time taken for mini-CEX assessments during the study period was 36.51 h. If extrapolated over a year this would represent an additional direct cost to the ED of more than $A 80,000 per year. No additional interns were identified as underperforming through the addition of the mini-CEX. The mini-CEX assessment process was perceived as generally positive. Both interns and assessors felt that it provided a valid assessment of intern performance, and enabled timely and specific feedback. Significant practical difficulties in arranging and conducting mini-CEX assessments in the workplace were identified. Conclusion: There was a significant cost to the ED as a result of adding mini-CEX encounters to interns' performance assessment. No change in summative outcome occurred for this study cohort.