On August 20, 2003, the Ministry of Health commissioned a study to determine the extent and epidemiological characteristics of the excess mortality associated with the heat wave. This article presents a summary of the main findings from the task force’s first interim report: the chronological development of excess mortality in August 2003; the relationship between mortality and temperature; the distribution of excess mortality by sex, age, geography, and place of death; and the medical causes most frequently involved. (R.A.)