Introduction: The aim of this study was to compare the educational performance of students in doctor of dentistry before and during the Corona pandemic in Ahvaz Jundishapur University of Medical Sciences during 2021. Methods: The research was experimental and carried out in terms of post-event method. The statistical population was 250 of dental students in Ahvaz Jundishapur University of Medical Sciences, and then they were selected as a sample by simple random sampling according to the Georgian and Morgan table. In the descriptive part, the indicators related to the mean and standard deviation,and in the inferential part, the independent and dependent t-test was used to test the hypotheses. Next, SPSS software version 23 was used for analysis that a significance level of 0. 05 was considered. Results: According to data analysis, the results showed that the mean of scores during and before Corona pandemic in obtaining the score of credit “, Oral and Maxillofacial Pathology course (1)”,was equal to 15. 98 and 12. 41, respectively,regarding to credit “, Anatomy of the Practical tooth”, , the mean score during Corona was 0. 00. 17 whereas it was 12. 14 before Corona pandemic,and also the mean of scores obtained in credit “, Internal diseases (2)”,was equal to 16. 48 and 12. 54 during and before Corona pandemic, correspondingly,next, for the credit “, Pharmacology”, , the mean of intracorona scores was obtained 17. 00 while the mean was 12. 30 before pandemic,and finally, the credit “, Oral and Maxillofacial Surgery (1), the mean score during Corona pandemic was measured 16. 95 while it was equal to 12. 62 before the pandemic. Conclusion: The results of the comparative t test showed that there was a significant difference between the average grades of students in the specialized courses examined before and during the Corona pandemic, and also the average grades increased during the Corona period.