Infant and early childhood death caused by environmental hyperthermia (fatal heat stroke) is a rare event, typically occurring in vehicles or beds. The aims of this study were to describe the demographics, circumstances, pathology, and manner of death in infants and young children who died of environmental hyperthermia and to compare these cases with those reported in the literature. Scene investigation, autopsy reports, and the microscopic slides of cases from three jurisdictions were reviewed. The subjects in 10 identified cases ranged in age from 53 days to 9 years. Eight were discovered in vehicles and 2 in beds. When the authors' cases were grouped with reported cases, the profile of those in vehicles differed from those in beds. The former were older, were exposed to rapidly reached higher temperatures, and often had more severe skin damage. The latter were mostly infants and were exposed to lower environmental temperatures. Hepatocellular necrosis and disseminated intravascular coagulation were reported in victims who survived at least 6 hours after the hyperthermic exposure. The consistent postmortem finding among nearly all victims was intrathoracic petechiae, suggesting terminal gasping in an attempt at autoresuscitation before death. The manner of death was either accident or homicide. Recommendations for the scene investigation are made.