Purpose: The purpose of this study is to evaluate the accuracy of standardized patients’ (SP) rating according to the order of examinees in clinical performance examination. Methods: In the clinical performance examination which was administered in 2005 at Seoul National University College of Medicine, each SP evaluated 16 students consecutively. For all 16 SPs (2 SPs per station), accuracy of rating was evaluated by comparing the individual records of each SP to the ‘recording keys’ made by two SPs from reviewing a video recording of performances by examinees. Results: The average number of items incorrectly rated by SP was 3.8 (range, 0~12), 2.8 in female SPs and 4.8 in male SPs (p<0.001). No statistical correlation was observed between the number of errors and the order of examinees (p=0.843). Even after stratification by gender or age of the SPs or domains of examination, the number of items incorrectly rated did not differ significantly according to the order of examinees. Conclusion: An increase in SP’s rating error with time after the start of examinations was not observed within the 16 consecutive encounters in clinical performance examination. The effect of SP’s fatigue on the accuracy of simulation as an examination progresses remains to be studied.