In the wake of the 2003 heat wave, many European countries implemented action plans that included public health warning systems, surveillance measures, and modifications to existing infrastructure. The 2006 heat wave also led to excess mortality. Although few countries have reported data, the impact on mortality appears to have been much less significant in 2006 than in 2003. Nevertheless, in most of Western Europe, the 2006 heat wave was less severe than that of 2003. It is therefore not possible to attribute the reported decline in mortality in these countries solely to the effectiveness of "heat wave" plans. A more detailed assessment of the effectiveness of "heat wave" plans will be necessary to clarify this point. It is projected that the extreme temperatures of 2003 will become common in Europe within a few decades as a result of global climate change. In this context, we must ensure that public health responses to heat waves are capable of addressing future climate change and do not exacerbate climate instability through increased energy consumption. The scope of interventions aimed at reducing the health impacts of heat should not be limited solely to health warning systems and emergency responses. We must also consider the influence of urban design, transportation policies, and building codes on our energy consumption in both summer and winter, as well as the social and public health consequences of climate change adaptation and energy efficiency measures. (R.A.)