In 2006, an increase in leptospirosis-related mortality on Réunion Island prompted concern among public health authorities, even though the most recent epidemiological data published on the disease on the island dated back to 2003. Conducted in this context, the objective of this study was to update knowledge on the epidemiology of leptospirosis on Réunion Island. It was conducted as a retrospective descriptive study using data from the reporting and investigation system for hospitalized leptospirosis cases in Réunion between January 1, 2004, and December 31, 2008. Data from the National Reference Center (CNR) were also utilized. The annual number of reported cases (40 to 50) remained stable over the period, and the circumstances of exposure were consistent with those typically associated with the disease on the island: nearly 80% of patients were infected during the wet season; the primary risk factor identified was working in agriculture. Although on the decline, Leptospira icterohaemorrhagiae remained the primary serovar isolated. Finally, our study showed that the excess mortality observed in 2006 resulted from an increase in case fatality rather than in incidence. This situation could be linked to the 2006 chikungunya epidemic. In areas where leptospirosis is endemic, it therefore appears necessary to take into account the risk of fatal cases of the disease when an arbovirus epidemic occurs. (R.A.)