Background: The doctor-patient relationship may be affected by the indiscriminate use of social media platforms. The aim of this study was to evaluate the content of the photos posted on medical students’ Facebook accounts to determine whether they have posted private patient information and compare this to their self-reported behavior of posting such photos. Methods: We performed a cross-sectional study of medical students from a Peruvian private university. With their permission, we reviewed their Facebook accounts for the publication of photos or documents that included private patient information (face, name, diagnosis, medical exams). Those who allowed access to their Facebook accounts were also asked to complete an online survey. We assessed variables related to sociodemographic aspects, self reported Facebook use, and what type of private patient information they posted. Results: A total of 160/220 students joined the study, 59% were women, mean age: 20 years. 25.7% self-reported having posted private patient information in their Facebook profiles but we found such information on 33.1% of the students’ pages. Of the pages where private patient information was found, in 94% of cases, the patients’ faces were identifiable, and in 7.6%, the patients’ real names appeared. However, only half of the students believed that the information in their Facebook post might affect or influence the doctor-patient relationship. Association with narcissism, gender, and account privacy was not found. Having uploaded more than 250 photos (OR:2.90; CI95%:1.14-7.39) and posting photos tagged with the location of a hospital (OR:4.02; CI95%:1.36-11.9) were associated with having posted photos containing private patient information. Conclusion: One out of three of medical students posted patients’ private information on their personal Facebook profiles. Development, dissemination, and implementation of guidelines related to ethics in social media platforms are needed.