In August 2009, a nursing home for the elderly in the Vaucluse department reported seven suspected cases of influenza. Since the nasal swabs taken to test for the novel 2009 H1N1 virus came back negative, heat-related health issues were suspected. An investigation was conducted. A case was defined as the onset of fever between August 21 and 24, with or without respiratory or systemic symptoms. Data were collected from medical records and from the medical staff. Seven of the 78 residents presented with heat-related conditions. Risk factors for heat-related health issues, as described in the literature, were identified both at the individual level (multiple comorbidities, use of numerous medications, loss of independence) and at the environmental level (urban building, rooms facing southeast and southwest, rooms on the top floor). The investigation showed that, despite the existence of procedures, the management of cases proved inadequate and delayed. Indeed, several warning signs did not trigger a response (hypernatremia, heatwave alert activation, etc.), and it was a procedure for influenza—not for a heatwave—that triggered the alert. Training sessions involving feedback exchanges between nursing homes and within specialized facilities are recommended. (R.A.)