Background - In the context of climate change, it is important to better understand the relationship between extreme temperatures, healthcare utilization, and mortality in order to improve prevention efforts and mitigate the impact of heat waves. Method - A literature review analyzed articles published up to January 2013 on the impact of heat waves or high temperatures on indicators of healthcare utilization. Results - Thirty-nine articles were selected, including two concerning France. Twenty-four presented time-series analyses of the impact of temperature on emergency department visits and hospitalizations. Most studies highlight a much greater impact on mortality than on morbidity, particularly when considering aggregate indicators. Healthcare utilization for hyperthermia shows the most marked increase. Temperature has a more moderate impact on emergency room visits or hospitalizations for renal or respiratory conditions. Discussion - Few studies describe the impact of heat waves on healthcare utilization indicators. The most pronounced increases are observed in mortality. This makes it difficult to interpret healthcare utilization indicators for early warning purposes: a small impact on morbidity could mask a larger impact on mortality. (R.A.)