Objectives: This study investigates a potential increase in mortality and in the demand for ambulance emergency services among the elderly in particular, in Ticino in the summer of 2003. Methods: Mortality rates and emergency ambulance interventions rates were compared with records from the previous years. We considered the whole population, aged 65 and over, as well as 75 and over. Results: The 2003 mortality in the population was not significantly different from the previous years. The number of deaths among the elderly showed a small but significant deviation from the expected values during the first heat wave in June 2003, with no significant impact on the seasonal results. The number of ambulance service interventions was larger than during the previous years. Conclusion: These results are consistent with findings in other studies. The heat waves (especially in June), were correlated with a higher number of ambulance callouts. In addition to some geographic, climatic, and social factors that had a protective impact, the response of the emergency services is likely to have contributed to a certain reduction in mortality. [Authors]