Immunological responses to influenza vaccination administered to liver transplantation recipients are not fully elucidated. To compare inactivated influenza vaccine's immunogenicity between adult and pediatric recipients, 16 adult and 15 pediatric living donor liver transplantation recipients in the 2010–11 influenza season, and 53 adult and 21 pediatric recipients in the 2011–12 season, were investigated. Seroprotection rates (hemagglutinin-inhibition [HI] antibody titer 1:40) were 50–94% to all three antigens among adults and 27–80% among children in both seasons. Seroconversion rates (fourfold or more HI antibody rise) were 32–56% among adults and 13–67% among children in both seasons. No significant differences were observed between the two groups. In addition, 20/53 adult and 13/21 pediatric recipients received a vaccine containing identical antigens in both of these seasons. Geometric mean titer fold increases of all three antigens in adult recipients were significantly lower than those in recipients who had not received a preceding vaccination. In contrast, in pediatric recipients, there were no significant differences between the groups who had and had not received preceding vaccinations. The number of patients with rejection did not differ significantly between the two groups (0/53 vs. 1/21) in the 2011–12 season. The incidence of influenza after vaccination was significantly different between adult and pediatric recipients (0/16 vs. 5/15 in 2010–11 and 0/53 vs. 3/21 in 2011–12, respectively). Overall, there were no significant differences in antibody responses between adult and pediatric groups. Influenza infection was more frequent in pediatric recipients. Long-term response to preceding vaccinations appeared to be insufficient in both groups.