Introduction: Abuse and cyberbullying have existed for a long time, however, the pandemic could be a risk factor that negatively impacts the self-esteem of medical students. The objective of this study was to determine the association between mistreatment and cyberbullying with self-esteem in medical students at a Peruvian university during the COVID-19 outbreak.Methods: Observational study, analytical type, carried out in 271 students from first to sixth year in a Peruvian medical school. The presence of abuse, cyberbullying and self-esteem were evaluated using the Perception of Abuse Questionnaire in Medical Students, the European Cyberbullying Intervention Project Questionnaire Spanish version (ECIPQ) and the Rosemberg Self-esteem Scale, respectively. Bivariate using the chi square test (significance level of p<0.05).Results: The perception of psychological abuse was 237 (87.50%), academic 237 (87.50%), and sexual 136 (50.90%); 67 (24.70%) of cybervictims, 35 (13.70%) of cyberbullies, and 35 (13.30%) of victimized cyberbullies were found; the majority of students had an average self-esteem of 111 (41.69%). The level of global self-esteem was significantly associated with the presence of psychological (p = 0.001), academic (p = 0.018) and sexual abuse (p = 0.000), but not with the presence of cybervictims (p = 0.090), cyberbullies (p = 0.107) and with the victimizing cyberbullies (p = 0.178).Conclusions: An association was found between the perception of psychological, academic and sexual abuse with the level of global self-esteem, in contrast, there was no evidence of the influence of cyberbullying on the self-esteem of the medical student.