Heat shock proteins (HSPs), are a group of proteins that function as intra-cellular chaperones for other proteins. They are expressed by cells in response to exposure to stress conditions. The aim of the present study was to evaluate the role of heat shock protein 70 (HSP70) expression as vitality marker in identification death due to fatal thermal exposure (fire). This study was carried out on 21 cases of fire related fatalities (group I), 21 cases of acute traumatic death without any evidence of antemortem thermal exposure (group II). All autopsy cases of group I were examined regarding the degree of burn, carbon soot aspiration and survival time. Carboxy hemoglobin (COHb) blood level was assessed. Immunohistochemical examination of lungs, kidneys, heart and liver in all cases of both groups was done. Cases of group I showed significant strong positive HSP70 immunoreactivity (grade 3) in the lung and kidney sections either with short or long survival time exposure when compared with cases of group II. Sections from heart and liver in both groups showed weak HSP70 immunoreactivity. There was no association between the degree of HSP70 expression and degree of burn, presence or absence of carbon soot and COHb concentration in blood in group I. It was concluded that the immunohistochemical investigation of HSP 70 expression in lungs and kidneys can support the proof of vitality in death due to fatal thermal exposure.