To determine if the influenza vaccine can reduce absenteeism and the cost of Influenza-Like Illness (ILI) in healthy adults in the workplace, a prospective, non-randomized, non-placebo control trial was done in six North Carolina textile plants. One hundred thirty-one vaccinated employees were compared with 131 age- and gender-matched non-vaccinees from different plants. Twenty-six (20%) of the vaccinated and 64 (49%) of the unvaccinated group had ILI (P = 0.0000008). Fifteen (11%) of the vaccinated and 31 (24%) of the unvaccinated employees missed work because of ILI (P = 0.01). There were 43 lost workdays in vaccinated and 93 in unvaccinated employees (P = 0.00004). The "cost per saved lost workday" was $22.36, for a company savings of $2.58 per dollar invested in the vaccination program. We concluded that the influenza vaccine can give significant reductions in incidence, absenteeism, and cost associated with ILI in the workplace.