Abstract: An 84-year-old woman is reported whose death was associated with strenuous exercise on an extremely hot day (maximum temperature = 43.1°C, 109.6°F). At autopsy there was evidence of exposure to high environmental temperatures with early putrefactive changes and mummification. There was underlying cardiomegaly with mild pulmonary emphysema. No significant injuries were detected. Toxicology revealed therapeutic levels of oxybutynin prescribed for urinary stress incontinence. Death was considered to be heat related, exacerbated by oxybutynin therapy, exercise, and cardiomegaly. Given that it has been predicted that there may be an increase in the number of heatwaves and in their intensity and duration, it is possible that such cases may be encountered more often in future. The assessment of all deaths occurring during conditions of extreme heat will require consideration of postmortem toxicology, particularly if there are underlying conditions such as stress incontinence that may be associated with anticholinergic drug therapy.