Objective To analyze the concepts related to Patient Safety and Error expressed in Brazilian official documents, from the perspective of complex thinking. Method Documentary research on the websites of the Federal Official Gazette, Ministry of Health, and Patient Safety of the Brazilian Health Regulatory Agency. The descriptors Patient Safety and Medical Error were used in the period from 1999 to 2020. The excerpts were treated following the Content Analysis technique, developed in three stages: pre-analysis; exploration of the material; and treatment of results. Results Of the total of 498 documents, nine were selected and originated the categories: Meaning of patient safety and Concepts related to the meaning of error. Final considerations Patient safety refers to protection, risk minimization and harm prevention, continuous improvements, good practices, and quality of care. An error refers to an incident, adverse event, and harm. To prevent an error, it is necessary to recognize and understand it as an event inherent to health services. Thus, rationality protects us from error and illusion, allows thought advancement, accepts self-criticism and argument contestation, expands understanding and development of knowledge.