Carbon monoxide poisoning is not easily identifiable. It is the first cause of death by accidental poisoning in Europe. The family practitioner, who has not been made aware of this problem, incurs the risk of diagnostic indecision or of involuntary personal poisoning. Since symptomatology is non specific, the general practitioner answering housecalls is sometimes confronted with an urgent medical problem linked to the complications of this intoxication (coronary, neurological problems...), without having ways of documenting its origin of the poisoning or any means to protect himself. Through direct contact with his patients' environment, the family practitioner, being made sensitive to this problem, can certainly contribute to care and aftercare of the patient suffering from carbon monoxide poisoning, but also to the prevention of this public health problem often called "the silent killer".