OBJECTIVE Self-assessment is a fundamental skill for dentists and other health care providers. It enables these professionals' ability to critically evaluate the quality of their clinical work and improve through self-directed learning. Researchers have investigated how gender affects self-assessment skills and have shown that male students tend to overestimate their performance while female students tend to underestimate theirs as compared to peer or faculty assessment. The goal of this study was to evaluate how the self-assessment skills of dental students differ by gender in operative preclinical dentistry. METHODS Third-year dental students (N = 208, Class of 2016-2021) self-assessed their work using the same rubrics as faculty on four operative dentistry competency examination procedures: Class II amalgam preparation and restoration and Class III resin-composite preparation and restoration. Two calibrated full-time faculty graded all procedures independently. The Student self-assessment-Faculty grade (S-F) gap scores were calculated and statistically analyzed. RESULTS Overall, both genders overestimated their self-assessment for all four procedures as compared to actual scores given by faculty. Males overestimated more significantly than females for Class II Amalgam preparation, but not for the other three procedures. However, when the S-F gap for all procedures was combined and analyzed together, male students significantly overestimated their self-assessments compared to female students. When female and male students grading scores were stratified into quartiles, there were significantly larger differences between males and females in the lower quartiles, which suggest that difference in self-assessment abilities was more prominent among the lower performing students. CONCLUSIONS The results of this study demonstrate that gender may affect the accuracy of self-assessment in operative preclinical dentistry.