PURPOSE: Standardized patients participate in clinical performance examinations not only to simulate case scenarios but also to evaluate the performance of students using a checklist. The accuracy in checking off checklist items is one of the most important factors determining the reliability of this examination. The purposes of this study were to determine the SP' s overall accuracy in recording checklist items, and whether their accuracy was affected by certain characteristics of checklist items. METHODS: Three professors, who have been fully involved in scenario development and SP training, reviewed videotapes of the examination and evaluated the performance of the students using the same checklist. SP' s checklists were marked on this 'correct checklist'. The checklists and checklist guidelines of the items marked under the score of 50 out of 100 were analyzed. RESULTS: Results showed that the accuracy of the SP' s in recording checklist items was 86.9% and was affected by certain characteristics, such as complexity or ambiguity of checklists and checklist guidelines. CONCLUSION: In this study, the SP' s accuracy in recording checklist items was good to very good, and the result suggested that the accuracy could be improved by the elaboration of checklists and checklist guidelines.