Seasonal influenza is a prevalent and highly contagious acute respiratory disease that, year on year, results in increased morbidity and mortality on a global scale. Because of the widespread and debilitating nature of the disease, annual influenza epidemics result in substantial workplace absenteeism, and the associated cost of lost productivity is a significant component of the substantial financial burden of the disease to society. The objective of this review was to identify studies that had attempted to quantify the impact of influenza upon otherwise healthy adults in terms of working days lost associated with an episode of influenza.Studies were included if they reported estimates of working days lost due to clinical, physician and/or self-diagnosis in adult patients or their dependants, or where this figure could be estimated from the data. Searches were conducted in MEDLINE, EMBASE, BIOSIS and the Cochrane Collaboration for articles published since 1995 in English, French or German. Of the 289 papers identified in the search, 28 (9.7%) met the inclusion criteria. The studies, involving study sites in North America, Western Europe, Asia and Australia, were categorized into three groups: (i) those reporting influenza diagnoses confirmed by laboratory testing, i.e. studies where influenza was the unambiguous cause of the working days lost (n = 7 studies reported in ten publications); (ii) those where influenza was confirmed by a physician without an accompanying laboratory test (n = 4 studies); and (iii) those where influenza was self-reported by study participants (n = 14 studies). Qualitative reporting of results was performed because of the large degree of heterogeneity observed between studies, potentially complicating the interpretation of any meta-analysis.The results from studies involving a laboratory-confirmed influenza diagnosis suggested that the mean number of working days lost ranged between 1.5 and 4.9 days per episode. Those papers that detailed working days lost per episode following physician diagnosis of influenza reported a range of 3.7-5.9 days per episode. Finally, estimates from papers reporting working days lost per episode of self-reported influenza ranged from <1 day to 4.3 days per episode.Influenza imposes a significant burden on society, and this review highlights the significant economic impact it causes, i.e. the loss of productivity caused by both absenteeism and by staff functioning at reduced capacity even after they have returned to work. A number of prophylaxis and treatment options exist for influenza and should be given serious consideration in an attempt to reduce the economic burden on society.