OBJECTIVES: Influenza is a major cause of illness, productivity loss, and work absenteeism among healthy working adults aged between 25 and 64 years. This group is not included in the national Dutch influenza vaccination program, that encompasses the elderly of 65 years and older. The objective of this study is to estimate the cost and benefits of vaccinating healthy working adults aged 25 to 64 years against influenza. METHODS: Our cost-benefit analysis includes the direct and indirect costs associated with vaccination as well as the direct and indirect costs avoided by vaccination. The underlying model links influenza incidence to health-care resource use, work absenteeism and productivity loss. Health-care resource use was specified for general practitioner visits, hospitalisations and drugs. Clinical and economical parameter estimates were derived from published literature and Dutch registry data. RESULTS: Vaccinating healthy working adults aged 25 to 44 years costs € 0,39 per person per year. Vaccinating persons aged 45 to 64 years saves € 1,51 per person per year. On the population level, vaccinating persons aged 25-44 year costs about € 1,4 million per year, vaccinating persons aged 45-64 year saves about € 2,3 million per year. On average, vaccinating healthy working adults saves € 0,9 million. The indirect costs prevented primarily determine the cost-benefit outcome of vaccination for healthy working adults. CONCLUSIONS Influenza vaccination of healthy working adults is cost saving. These findings support routine vaccination for this group, from the employer’s perspective.