Introduction - A major chikungunya outbreak affected Réunion between March 2005 and June 2006, affecting nearly 270,000 people. This study aims to describe mortality during that same period. Methods - The observed number of deaths in 2005 and 2006 was compared to the expected number, estimated based on age- and sex-specific mortality rates for the 2002–2004 period and population estimates for 2005 and 2006. Death counts were derived from an automated data upload from 13 municipalities on the island whose civil registries are computerized. Results - In 2005, the observed number of deaths was close to expected values. In 2006, mortality rose sharply and significantly exceeded the expected value between weeks 4 and 10; between January and April 2006, the monthly variations were +7.1%, +34.4% (p<0.01), +25.2% (p<0.01), and +10.1% (p<0.01), representing a total excess of 230 deaths (based on the 13 municipalities) and 267 for the entire island. The excess mortality primarily affected those aged 75 and older. Starting in May 2006, observed mortality returned to its usual range of fluctuation. This trend closely mirrors that of the epidemic. Discussion-Conclusion - These observations suggest that the excess mortality during the first four months of 2006 is associated with the epidemic, as no other known health phenomenon capable of explaining this increase affected the island during this period. (R.A.)