The free circulation of people, goods, and foods within the European Union (EU) states has increased the opportunity for international outbreaks of foodborne infections despite prevention efforts to reduce microbiological contamination of foodstuffs. The implementation of the Enter-net (previously Salm-Net) international surveillance network should lead to earlier recognition and investigation of these international outbreaks. The detection of an outbreak needs additional investigation to identify the vehicle and the source of contamination if appropriate control measures are to be taken and primary prevention improved. The investigation of an international foodborne outbreak at the European level follows the same principles as those used for national, regional, or local outbreaks, but the participation of many institutions from different countries makes the management of the investigation more complex. In addition, as countries may differ in their approach to and perspective on the problem, policy issues need to be considered. This paper proposes management principles for investigation of such outbreaks to facilitate collaboration between affected countries. It complements the principles of collaboration already agreed between Enter-net participants. (Extrait)