Global warming is now recognized worldwide. Thermoregulation is critical for human survival when exposed to a severely hot environment. Thermoregulation is closely related to physical fitness, but fitness decreases with advancing age. Thus, thermoregulatory functions also decline with age. In fact, several major heat waves have occurred around the world in the last 10 years, and the mortality ratio was further elevated in elderly people. We encourage exercise training in the elderly to maintain physical fitness, but we should also recognize how human thermoregulation alters with aging. The primary role of thermoregulatory functions is to maintain the internal body temperature within a narrow range. Internal body temperature is regulated by the thermal balance between heat production and heat dissipation. Older individuals have relatively low heat production, impaired thermal perception, and reduced autonomic and behavioral thermoregulatory responses. However, these diminished thermoregulatory functions can be improved, although the gain is lower or limited relative to their younger counterparts. We summarize thermoregulatory functioning in elderly people based on recent publications and our findings.