AIMS To analyse the relationship between high temperatures and population health impacts, in terms of mortality and morbidity. METHODS A literature search was conducted using Medline to collect data from studies on heat waves, temperature-health impacts curve, risk factors, and preventive measures. All the data collected was published in English and available up to December 2009. RESULTS Numerous studies carried out in Europe following the 2003 heat wave, as well as those conducted prior to this date in Europe and North America, showed an increase in heat wave-related excess mortality. Recent studies have demonstrated that a forward shift of deaths may only explain a very limited quantity of the excess mortality observed (up to 15%) during major heat waves. Moreover, the results seem to exclude that ozone acts as a confounding variable, whilst it remains a potential effect modifier. CONCLUSIONS Future research needs to explore the consistency of results in new settings, to quantify the burden of heat-related morbidity and in particular to evaluate the effectiveness of the implemented preventive measures.