The systematic application of combustion theory to problems of biological energetics is a field which has hardly been exploited to any great extent, and in this article many opportunities for such exploitation are suggested. The balance between heat generation and heat loss in biological systems is shown to lead to steady states and also to the disappearance of the latter at various critical conditions, including hypothermia, hyperthermia and hibernation. Other physiologically interesting concepts, such as the existence of a body temperature of optimum stability, are discussed from the combustion point of view. The possible occurrence of thermally coupled oscillations in the biological sphere is discussed in the light of the occurrence of regions of negative temperature coefficient in the metabolic rate curves of many species. The distribution of temperature in self heating tissues is also discussed as is the formal parallel between the propagation of a flame and a nerve impulse, both having a characteristic velocity and a nonlinear positive feedback process.