Background: Heat exposure represents an occupational risk factor in various work settings. Adverse effects may range from mild symptoms, like muscular cramps, to life threatening conditions, like heat stroke. Data on the occurrence of work-related adverse effects of heat exposure in Italy are lacking., Objectives: To highlight the risk of heat stroke in a common working activity., Methods: The case of a fatal heat stroke in a 19-year-old worker, in apparently good health, employed in maintenance of open park spaces is presented. After working 7 hours outdoors on a sunny day he was found unconscious. He was immediately taken to the local Emergency Department, where he arrived in hyperthermic and comatose conditions, and died due to multiple organ failure after 36 hours. After excluding other main causes of hyperthermia, heatstroke was identified as the initial cause of death., Results: The case presented describes the possible extreme consequences of an underestimation of the risk related to occupational heat exposure, even in young and apparently healthy workers. Heat-related adverse effects may occur in a number of common activities, not necessarily involving heavy workload or extreme temperatures. Different methods, including simplified methods, are available for heat stress risk evaluation. The main preventive measures include adequate acclimatization, periodic interruption of exposure, sufficient fluid intake, adequate clothing and appropriate Personal Protective Equipment. Adequate training and workers' health surveillance are also essential., Conclusions: Heat exposure may be a significant occupational risk, potentially inducing life-threatening conditions, in a number of common activities but is frequently underestimated. An example of undervaluation of the risk and of the possible consequences, are presented and discussed in this case report.