Vaccination is the most effective way to prevent influenza-related morbidity and mortality. Annual influenza vaccination was first recommended for children aged 6-23 months in 2004 and for children aged 24-59 months in 2006. In August 2008, the Advisory Committee on Immunization Practices (ACIP) expanded its recommendations to include all children aged 5-18 years, beginning with the 2008-09 influenza season. Among children aged 6 months--8 years, previously unvaccinated children and children who received only 1 vaccine dose for the first time in the preceding influenza season are recommended to receive 2 influenza vaccine doses. Children aged 9-18 years are recommended to receive 1 vaccine dose. To update previous estimates by assessing influenza vaccination coverage among children aged 6 months--18 years during the 2008-09 season, CDC averaged data from the eight immunization information system (IIS) sentinel sites. The results indicated that average (unweighted) vaccination coverage with >or=1 influenza vaccine doses decreased with increasing age from 47.8% for children aged 6-23 months to 9.1% for those aged 13-18 years. Among sites, average coverage with >or=1 doses among children aged 6--23 months increased from 40.8% during the 2007-08 influenza season to 47.8% during the 2008-09 season; however, coverage levels remained suboptimal. Vaccination against both seasonal influenza and 2009 pandemic influenza A (H1N1) are recommended for children in 2009; these findings highlight the need to identify opportunities for and barriers to influenza vaccination of children.