Carbon monoxide poisoning is one of the most frequent types of poisoning caused by gases. Exposure of a pregnant woman to carbon monoxide is connected with transmission of this gas to her fetus what may cause oxygen deficiency, and further, the damage to its organs. The article describes a case of carbon monoxide poisoning of a 28-weeks pregnant woman who was treated in a hyperbaric chamber. Therapy was successful and the woman gave birth to a healthy, full term infant. In case of poisoning to a pregnant woman the above seems to be the most advantageous solution.