Many studies world wide have provided evidence that older persons are a sub-population at increased risk of heat-related morbidity and mortality. This article gives an overview of the current state of knowledge of risk factors and provides commentary on the role of health promotion in the prevention of a climate change-related increase in elderly heat casualties. A search of peer-reviewed medical and epidemiological literature and community health websites was conducted in order to gain an in-depth understanding of heat-susceptibility in the elderly and preventive strategies. Key search words included: elderly, aged, older, heat, thermoregulation, heat wave, mortality, heat effects, dehydration, heat-related illness, adaptation, adaptive capacity. The reasons underlying reduced heat tolerance in this group are multi-faceted, comprising physiological, social and behavioural limitations, with comorbidities and polypharmacy being contributing factors. Additionally, some older persons may be unable or reluctant to undertake adaptations necessary to maintain thermal homeostasis due to diminished awareness of the heat, lowered thirst sensation, mobility or cognitive impairments, a lowered perception of risk, or economic concerns. With older persons in poor health being particularly vulnerable to heat, preventive messages need to promote protective behaviours and help build resilience as temperatures rise.