Introduction: Harassment against medical students, especially interns, is usually a constant within hospitals in Peru. This becomes a problem when it comes from physicians belonging to the same hospital. Objective: To determine the values of harassment and mistreatment of medical assistants and residents towards medical interns in different hospitals in Peru. Methods: A cross-sectional and analytical study was carried out, based on a survey on doctors who had recently done their internship. The NAQ-R test was used to assess harassment. Also, the respondents were asked about their perception about harassment and mistreatment that came from medical residents and assistants. Association statistics were obtained. Results: Of the 617 interns surveyed, the highest value for harassment obtained in the test corresponded to medical residents (RPa: 2.40; CI95%: 1.75-3.30; p value<0.001) and assistants (RPa: 2.08; CI95%: 1.57-2.75; p value<0.001). On the other hand, according to perception about harassment, it was higher in the interns who had performed their internship in more than one hospital center (RPa: 1.96; CI95%: 1.25-3.07; p value=0.003), but also among those who had perceived mistreatments by medical residents (RPa: 2.41; CI95%: 1.71-3.39; p value<0.001) and assistants (RPa: 1.80; CI95%: 1, 32-2.44; p value<0.001). Conclusions: It was found that there was mistreatment (by perception and the test) by medical assistants and residents, which is described as serious since it generates a toxic work and training environment. Thus, it is recommended to promote situational analyzes in each reality and interventions to break the vicious circle of mistreatment.