Introduction—Located in the subtropical zone of the Southern Hemisphere and, due to significant population movements, subject to the influence of neighboring regions where the risk of infectious diseases has not yet been brought under control (Madagascar, Mayotte, Comoros), Réunion presents specific characteristics regarding infectious diseases not only compared to mainland France but also to the French West Indies and French Guiana. The main objectives of this study were to identify the infectious diseases that health professionals in Réunion consider a priority for surveillance and to rank these diseases according to their public health importance at the regional level. Method - A questionnaire-based consensus method derived from the Delphi technique was proposed to a panel of healthcare professionals in Réunion involved in the diagnosis, management, or prevention of infectious diseases, following a protocol tested in the French West Indies and French Guiana. Results - The response rate among panel members exceeded 60%. A robust consensus was reached in two rounds of consultation to define priority levels for the surveillance of infectious and parasitic diseases in Réunion. Dengue, malaria, leptospirosis, HIV infections and AIDS, influenza and influenza-like illnesses, and tuberculosis are the diseases for which surveillance in Réunion is considered the highest priority by the healthcare professionals consulted. At a lower priority level are acute diarrhea, bronchiolitis, and hepatitis B and C. Numerous proposals for improving the surveillance system were put forward. Discussion and Conclusion - This type of study appears particularly useful for diseases where surveillance is justified by strong regional specificity, but its effectiveness is more limited for certain types of surveillance, such as the reporting of health events for alert purposes or the surveillance of emerging diseases. In this regard, this study provides essential insights that should be considered, among other factors, when defining the direction of surveillance in Réunion. Consequently, the healthcare professionals consulted largely endorsed the list of diseases already subject to local surveillance. However, they expressed numerous expectations regarding the current system, addressing which will require significant adaptation efforts, particularly with regard to communication with stakeholders on the ground.