Santé publique France conducted a study on the impact of heat waves on worker mortality and morbidity during the period when the Heat Wave and Health Alert System (SACS) was in effect, from June 1 to September 15, in 2018 and 2019. Regarding mortality, since 2017, Santé publique France has been organizing, in consultation with the Occupational Health Inspection, an early reporting system for information held by the General Directorate of Labor on fatal workplace accidents potentially related to heat. Eight deaths potentially related to heat were observed in 2018 and 10 in 2019. For morbidity, a two-part exploratory study was conducted in Île-de-France (IDF) and Provence-Alpes-Côte-d'Azur (PACA). The component conducted in IDF focused on the use of data from emergency department visit summaries (RPU) related to occupational activity. The health indicators were heat-related conditions and symptoms: heatstroke and hyperthermia, dehydration, and hyponatremia. Other indicators less specific to heat were also studied. A slight variation in health indicators was observed depending on temperatures. However, interpreting RPU data for work-related circumstances is difficult due to the small number of facilities coding the "circumstance" variable and the lack of information on the quality of coding for this variable. The component conducted in the PACA region focused on the analysis of data from SAMU dispatch records. The study examined health events occurring in the workplace or related to professional activity that prompted a call to SAMU. The results show that workplace interventions increase during heat waves. The observation of deaths during the SACS period underscores the importance of continuing to raise awareness on this issue among occupational health prevention stakeholders and of continuing surveillance in collaboration with the General Directorate of Labor. Given the results obtained, the nationwide rollout of the future RPU format (RPU V3) is an essential prerequisite for continuing the study of heat-related morbidity using RPU data linked to occupational activity. Similarly, we should await the results of the rollout of the Samu Information System (SI-Samu), which should eventually provide standardized data at the national level.