Purpose: The purpose of the study is to analyse the appropriateness of using standardized patients (SPs) assessment scores of medical students in clinical performance examination (CPX). Methods: 110 fourth year medical students in year four were divided into two large groups (group A and group B). Each group of students performed four different cases and overall, eight cases were tested. The examination were done by professors and the SPs using the same examination paper. Test scores were analysed per station and per each test domain. The differences between the two examiners were studied using paired t-test. Results: There were significant differences in the scores given out by the professors and the SP s in four out of the eight stations. According to the examination results of each domain, four cases showed significant differences in the history taking category, three cases in the physical examination, one case in the information sharing, four cases in clinical courtesy, and two cases in physician-patient relationship category. Cronbach s alpha scores of all stations were over 0.6, reflecting that the test items were appropriate for the examination. Conclusion: From the result of this study and according to many preceding studies, using SPs’ evaluation scores in CPX is appropriate. Some limitation of this study and ideas for improvement in using SPs in CPX are suggested.