The new national surveillance system has made it possible to track cases of carbon monoxide (CO) poisoning on an annual basis, starting January 1, 2005. An analysis of hospital morbidity data (1997–2005) from the Medical Information Systems Program (PMSI) and mortality data (1997–2002) from Cépi-DC (Inserm) was conducted by the Languedoc-Roussillon Interregional Epidemiology Unit (Cire). The objectives were to establish a regional overview of existing health data and to identify trends prior to 2005. The results show that the regional annual incidence of hospital stays due to CO poisoning averages 6.3 hospitalizations per 100,000 inhabitants. Nearly three-quarters of CO poisonings occur in winter (73%). The male-to-female ratio is 1.1, and the age group most significantly affected is 0–14 years. On average, 13% of patients were admitted to a hyperbaric chamber. Furthermore, the annual mortality rates, for all causes of poisoning combined, are 0.8 deaths per 100,000 inhabitants across the entire region. Deaths are distributed equally among the various causes of poisoning (accidents, fires, suicide). This study provides information that can help describe regional trends prior to the implementation of the new CO poisoning surveillance system. Primary prevention of CO poisoning includes public awareness campaigns before and during the winter season, as well as outreach to healthcare professionals to improve reporting. Epidemiological surveillance will provide information to help adapt prevention messages as needed. (R.A.)