BackgroundRespect for confidentiality is important to safeguard the well-being of patients and ensure the confidence of society in the doctor-patient relationship. The aim of our study is to examine real situations in which there has been a breach of confidentiality, by means of direct observation in clinical practice.MethodsBy means of direct observation, our study examines real situations in which there has been a breach of confidentiality in a tertiary hospital. To observe and collect data on these situations, we recruited students enrolled in the Medical Degree Program at the University of Cordoba. The observers recorded their entries on standardized templates during clinical internships in different departments: Internal Medicine; Gynecology and Obstetrics; Pediatrics; Emergency Medicine; General and Digestive Surgery; Maxillofacial Surgery; Plastic Surgery; Orthopedics and Traumatology; Digestive; Dermatology; Rheumatology; Mental Health; Nephrology; Pneumology; Neurology; and Ophthalmology.ResultsFollowing 7138 days and 33157 h of observation, we found an estimated Frequency Index of one breach per 62.5 h. As regards the typology of the observed breaches, the most frequent (54,6 %) were related to the consultation and/or disclosure of clinical and/or personal data to medical personnel not involved in the patient’s clinical care, as well as people external to the hospital. As regards their severity, severe breaches were the most frequent, accounting for 46.7 % of all incidents. Most of the reported incidents were observed in public areas (37.9 %), such as corridors, elevators, the cafeteria, stairs, and locker rooms.ConclusionsIn addition to aspects related to hospital organization or infrastructure, we have shown that all healthcare personnel are involved in confidentiality breaches, especially physicians. While most are committed unintentionally, a non-negligible number are severe, repeated breaches (9.5 %), thus suggesting a certain carelessness, perhaps through ignorance about certain behaviors that can jeopardize patient confidentiality.Electronic supplementary materialThe online version of this article (doi:10.1186/s12910-016-0136-y) contains supplementary material, which is available to authorized users.