This study aimed to assess the errors that happened during root canal treatment (RCT) and compare the quality of root canal fillings (RCFs) performed by different academic grades of dental students at Jouf University. Materials and Methods: a retrospective audit study was conducted to check the errors that occurred during RCT performed by seniors and undergraduates. The quality of the RCFs were evaluated, using digital periapical radiographs depending on previously validated criteria. Data analyses were performed using Statistical Package for the Social Sciences. Descriptive statistics were used for expressing the frequencies of variables and the Chi-square test was used for comparing different variables with a 0.05 level of significance. Results: overall, 332 endodontically treated teeth (566 root canals) were finally chosen for the study. Out of these treated cases, 156 teeth (47%) had a total of 287 recorded errors, mainly in posterior teeth. From the total number of errors, short obturation was the highest error occurred (29%), followed by lack of apical seal (25.1%). Root perforation was the least reported error (2.8%), proceeded by broken instruments (5.6%). A total of 13.2% of the errors were teeth left with unfilled canals, while 7.7% were for an overextended filling. There were no significant differences between the quality of RCF performed by different academic grades. Conclusion: depending on the current study, the quality of RCTs performed by seniors and undergraduate students was 53% acceptable. A clear plan should be applied to improve the quality of treatment outcomes of undergraduate students by implementing more effective preclinical training courses, increasing the ration of supervisor-to-students, and using more advanced modalities during treatment.