OBJECTIVE To describe the perceptions and attitudes of registered nurses (RNs) towards adverse events (AEs) in nursing care. BACKGROUND The professionals' subjective perspectives should be taken into account for the prevention of AEs in care settings. METHODS Schütz's social phenomenology was developed. Interviews were conducted with nine Intensive Care Unit RNs. RESULTS The following five descriptive categories emerged: (1) the occurrence of AEs is inherent to the human condition but provokes a feeling of insecurity, (2) the occurrence of AEs indicates the existence of failures in health care systematization, (3) the professionals' attitudes towards AEs should be permeated by ethical principles; (4) the priority regarding AEs should be the mitigation of harm to patients, and (5) decisions regarding the communication of AEs were determined by the severity of the error. CONCLUSIONS The various subjective perspectives related to the occurrence of AEs requires a health care systematization with a focus on prevention. Ethical behaviour is essential for the patients' safety. CONCLUSIONS Activities aimed at the prevention of AEs should be integrated jointly with both the professionals and the health care institution. A culture of safety, not punishment, and improvement in the quality of care provided to patients should be priorities.