Fluarix (R) is a trivalent, inactivated, split-virion influenza vaccine containing 15 mu g haemagglutinin from each of the three influenza virus strains (including an H1N1 influenza A virus subtype, an H3N2 influenza A virus subtype and an influenza B virus) that are expected to be circulating in the up-coming influenza season. Fluarix (R) is highly immunogenic in healthy adults and elderly, and exceeds the criteria that make it acceptable for licensure in various regions (including the US and Europe). In a large, phase III, placebo-controlled, double-blind trial conducted in the US (2004/2005) in subjects aged 18-64 years, postvaccination seroconversion rates against the HIN1, H3N2 and B antigens were 60-78% and respective postvaccination seroprotection rates were 97-99% in Fluarix (R) recipients. Another phase III trial conducted in the US (2005/2006) established the noninferiority of Fluarix (R) versus another trivalent inactivated influenza virus vaccine in subjects aged >= 18 years, including a subgroup of elderly subjects. In annual European registration trials, Fluarix (R) has consistently exceeded the immunogenicity criteria set by the EU Committee for Medicinal Products for Human Use for adults and the elderly. Fluarix (R) demonstrated immunogenicity in small, open-label studies in at-risk subjects. During a year when the vaccine was well matched to the circulating strain, Fluarix (R) demonstrated efficacy against culture-confirmed influenza A and/or B in a placebo-controlled trial in adults aged 18-64 years. In addition, Fluarix (R) vaccination of pregnant women demonstrated efficacy in reducing the rate of laboratory-confirmed influenza in the infants and reducing febrile respiratory illnesses in the mothers and their new-born infants in a randomized trial. Fluarix (R) was generally well tolerated in adults and the elderly in well designed clinical trials and in the annual European registration trials, with most local and general adverse events being transient and mild to moderate in intensity. The most common adverse reactions in recipients of Fluarix (R) were pain, redness or swelling at the injection site, muscle aches, fatigue, headache and arthralgia. In conclusion, Fluarix (R) is an important means of decreasing the impact of seasonal influenza viruses on adults and the elderly.