The beneficial effects of heat therapy in humans have been known for millennia. Passive heat therapy (evoked though exposure to hot water baths, hot sand immersion, sauna or use of specialised heating garments) induces a myriad of physiological responses. These include large increases in cardiac output and selective increases in skin, muscle, fat and bone blood perfusion in the extremities, head and torso, but the opposite response in the cerebral and visceral circulations. Aerobic metabolism rises in conditions of whole-body hyperthermia; yet the magnitude of the metabolic response is small, demonstrating a predominant role of thermal stimuli and thus thermosensitive mechanisms in the hyperthermia-mediated circulatory and thermoregulatory responses. When heat therapy is repeated, significant structural and functional adaptations occur. Long-tem thermotherapy is known to (i) increase resting blood flow and ankle-brachial pressure index, (ii) improve vascular endothelial function, cardiac function, insulin sensitivity, blood glucose homeostasis and arterial blood pressure, (iii) decrease pain scores, (iv) improve walking distance, and (v) provide symptomatic and functional benefit to a variety of patient populations. In this talk, I will discuss the acute physiological responses and chronic adaptations to heat therapy, with particular emphasis on the thermal mechanisms contributing to the control of circulation and how recent advances in knowledge and understanding afford new therapeutical applications to improve health and quality of life in individuals with low functional capacity.