The document “Guidelines for Writing Outbreak Investigation Reports” by the European Centre for Disease Prevention and Control provides practical guidance on how to prepare clear, structured, and scientifically sound reports after investigating a disease outbreak. It is mainly intended for epidemiologists and public health professionals, particularly participants in the ECDC Fellowship Programme. The guide explains the purpose of outbreak investigation reports and describes the recommended structure and content of such reports, including sections such as background, objectives, methods, results, and conclusions. It also outlines how to present epidemiological, laboratory, and environmental findings, interpret the results, and formulate public health recommendations. Overall, the document aims to standardize outbreak reporting, improve the quality and clarity of reports, and ensure that investigation findings can effectively support public health decision-making and future outbreak prevention.