A new technique to apply standard high temperature burn injuries and scalds under controlled conditions in living mice has been established. The difference between scalds and ‘dry’ heat injuries in terms of the mortality rate and the histological changes within the skin has been demonstrated. The relationship between the surface area injured and the animal’s body weight and total surface as a critical parameter with respect to survival or mortality has been established. A mechanism for toxin formation in mammalian skin after high temperature energy input has been offered. The physical and chemical characteristics of a specific burn toxin have been described. The toxic effect of the isolated product and the lethal burn injury in vivo upon kidney tissue, serum creatinine and urea have been shown. A direct correlation between the toxic compound and the mortality has been shown by protecting the animals from the toxin (a) by delayed toxin absorption; (b) by active immunization of the animals against the toxin, and (c) by serum (IgG) therapy using heterologous and homologous anti-toxic serum.