Smoke inhalation injury affects nearly one third of all major burn victims. Significant inhalation exposures must be suspected in persons who were entrapped in a closed space or who became unconscious during a fire. Each individual fire generates a characteristic smoke depending on the type of materials burnt, temperatures reached during pyrolysis, and the availability of oxygen to sustain combustion. In addition to variable amounts of thermal loads, firesmoke may contain mixtures of carbon monoxide, hydrogen cyanide, nitrogen oxides, and other highly irritating gases. Each constituent of firesmoke may potentially create pulmonary and systemic toxicities and must be considered in every victim of smoke inhalation.