It is well documented that fire-fighting involves strenuous activity in harsh environmental conditions. The combination of increased metabolic heat production and high ambient temperature will result in an elevated deep body temperature and heart rate. These responses will be exacerbated if the fire-fighter is dehydrated. The protective clothing worn by the fire-fighter reduces the heat gain from the environment, but can also add thermal strain by increasing work load and impeding metabolic heat loss. An inexperienced fire-fighter may be less economic and under greater psychological stress; this will affect both the work rate and performance. The extent to which all of these factors affect performance will also depend on the fitness level of the fire-fighter and how close they are to their maximum physical capacity. Therefore, there are many inter-related factors that influence a fire-fighter's response and ultimately his or her ability to perform the task. This review examines the physiological responses to fire-fighting and discusses the factors that may impact on fire-fighter performance.