We used a Monte Carlo mathematical model to calculate the net economic returns (cost-benefit analysis) from annually vaccinating children against influenza. The model included cohorts of 1000 children in three different age groups (6-23 months, 6-59 months, and 5-14 years), with different proportions of children with high risk conditions (100, 10, and 0%). Vaccinating cohorts of 100% high risk children in all three age groups produced median net savings, regardless of cost of vaccination examined (US dollar 30-60/dose administered). Median threshold vaccination costs for cohorts containing 10% high risk children were US dollar 48, 46, and 45 per dose administered for age groups 6-23 months, 6-59 months, and 5-14 years, respectively (US dollar/dose administered below these thresholds generate net savings). For all cohorts, for the range of cost per dose administered examined, the 5th percentiles were net costs. The probability of death, though rare, was the most influential distribution in the model. The number of high-risk children that receive influenza vaccine should be maximized to achieve improved health outcomes as well as cost savings.