On 30 August 2007, the Italian Ministry of Health, through the Early Warning and Response System (EWRS) and under the revised International Health Regulations (IHR) (2005), notified the EU Member States, the European Centre of Disease Prevention and Control (ECDC) and the IHR contact point of the World Health Organization (WHO) regional office for Europe, of a laboratory-confirmed outbreak of chikungunya fever in the region of Emilia-Romagna in north-eastern Italy. At the time of notification, 131 suspected cases had occurred since the first (then known) case with onset of symptoms on 4 July. The majority of cases were reported from two neighbouring small villages (Castiglione di Ravenna and Castiglione di Cervia) in the province of Ravenna. The outbreak of chikungunya fever in north-eastern Italy is the first documented local vector-borne transmission of Chikungunya virus within the European main land. Considering the presence of the vector Aedes albopictus in other EU countries, and therefore the risk of spread to these areas, the Italian health authorities agreed on a joint ECDC/WHO visit, to assess the risk of establishment of local transmission and spread to other EU regions. In order to ensure an optimal outcome of the visit, ECDC invited international experts in epidemiology, virology and entomology, with specific experience in investigating and controlling chikungunya fever outbreaks. The objectives of the visit were: to assess the risk of establishment and spread of Chikungunya virus transmission in the EU following the establishment of local transmission in the provinces of Ravenna and Forli-Cesena in north-eastern Italy; to explore its potential implications for the EU and other European countries; to advise Italian health authorities on investigation and control issues.