An outbreak of gastroenteritis involving 26 guests of a wedding dinner occurred in August 2007 in Réunion Island, a French Overseas Department. Salmonella was isolated in 61.5% of cases and the two isolates serotyped were of serovar Weltevreden. We believe this to be the first food-borne outbreak due to S. enterica serovar Weltevreden described in Réunion Island. The epidemiological and environmental investigations of this outbreak did not provide enough evidence to identify a single vehicle of infection. It is necessary to improve surveillance of salmonellosis by multidisciplinary cooperation between clinicians, epidemiologists, microbiologists and veterinarians on Réunion Island. (R.A.)