Mistreatment of medical students is a major source of stress for them. Studies indicate a high incidence of such mistreatment, especially in clinical settings. In most cases, students who have been mistreated do not report it to the authorities. This study investigated factors related to the failure to report mistreatment. This was a cross-sectional study carried out in Kerman Medical School, Iran. All students in the internship and clerkship stages, as well as residents, were selected through the census method. Experiences of mistreatment and the reasons for not reporting them were evaluated using a questionnaire. The data were analysed with SPSS 19. Ninety-three per cent of the participants experienced mistreatment, but less than half of them reported it. Residents and interns reported emotional and academic mistreatment, respectively, more than other groups. The most common reason for not reporting mistreatment was that the students did not think reporting would accomplish anything. Our study showed that the experience of mistreatment in the clinical setting is common, but the cases reported to the authorities are far fewer than the actual number of cases. Educational systems should make extensive efforts to detect and prevent mistreatment to improve the teaching–learning environment.