To combat carbon monoxide (CO) poisoning, which causes approximately 100 deaths and several thousand hospitalizations each year, a national CO poisoning surveillance system has been established to issue alerts, estimate the scale of the problem, describe the circumstances of occurrence, characterize the victims, and evaluate the public health measures implemented. The system relies on reports from individuals who have become aware of any suspected poisoning and is based on five environmental and medical questionnaires. In 2006, 1,682 cases of CO poisoning were reported, 76.9% of which occurred between October and March. Accidental CO poisonings in the home (n=1,069) were associated in 75.5% of investigated cases (n=799) with the presence of at least one contributing factor, such as a ventilation problem, improper use, or a defect in the appliance. A medical survey was conducted among 3,811 victims of CO poisoning out of 1,432 cases of CO poisoning (representing a rate of 6.2 cases per 100,000 inhabitants). For 46.0% of the victims, no symptoms were observed at the time of diagnosis. The main symptoms observed were headache (75.9%), nausea (39.9%), and dizziness (28.7%). Emergency room treatment was provided for 62.0% of those poisoned, and 32.1% of them were hospitalized. Although the CO poisoning surveillance system has made it possible to characterize CO poisoning across the entire metropolitan area for the first time, it must evolve to better meet the system’s alert objectives in order to more effectively detect emerging situations involving CO poisoning episodes. (R.A.)