OBJECTIVES: To evaluate cost of children and adults diagnosed with seasonal influenza in Germany, filling a data gap of more than a decade.  METHODS: This cost-of-illness study was conducted from payer and societal perspective based on a retrospective database analysis by using a longitudinal electronic medical records database (IMS® Disease Analyzer). Patients with influenza episodes (ICD-10 diagnosis J09-11) being observable 12 months before index date and 1 month afterwards were included. The selection window was May 2010 to April 2012 to cover two influenza seasons. Published unit costs and tariffs for Germany in 2012 were used. RESULTS: 23,068 influenza episodes (19,446 patients) managed by primary care practitioners (PCP) and 7,295 episodes (5,988 patients) managed by pediatricians were eligible for analysis. Mean age of patients with at least one episode was 43 years (SD 20) in the PCP panel and 7 years (SD 4) in the pediatrician panel. Total average mean cost (SD) from societal perspective in adult patients was €471 (576) and in children €99 (140)/episode. In about 11% of the adult patients the total cost exceeds €1,000/episode. This is primarily due to the higher percentage of patients with complications (63%) compared to the entire PCP study cohort (38%). Workdays lost were the main cost driver (82%) in adult patients; more than 40% of patients missed between 2 and 6 days of work/episode. In children, the main cost driver was physician visits (66%). Complications increase the cost by three fold in children and two fold in adults (average mean cost (SD) for children: €137 (144) vs. €49 (33) and adults: €622 (670) vs. €377 (485)). CONCLUSIONS: Results based on a large and representative patient sample demonstrate that the cost of seasonal influenza episodes is substantial, especially when complications occur. Costs in children may be higher of what is actually reported.