According to Météo France, the summer of 2003 was the hottest in 53 years in terms of maximum temperatures (2°C above the three hottest summers on record: 1976, 1983, and 1994) and, importantly, for minimum temperatures (3.5°C above the 1950–1980 average). Figure 1 shows that temperatures exceeding 35°C were recorded at two-thirds of the weather stations across France between August 1 and 18, 2003. The objective of the study is to compare the daily number of child hospital admissions during the August 2003 heat wave with data from the years 2000–2002 in order to identify a possible increase in pediatric hospital morbidity during this period. This initial estimate is based on hospitalization data from the Medical Information Systems Program (PMSI).