Objective: Seasonal influenza vaccination is place an important role in the prevention of children with chronic disease. However, the vaccination rate in this group is sub-optimal and far from the public health goal. The aim of this study is to contribute to research addressing the need for a higher rate of seasonal influenza vaccination of chronically ill children at our center. Material and Methods: This study was conducted in Ankara Child Health and Diseases, Hematology Oncology Training and Research Hospital and is a single-center retrospective study. The study covers 3 consecutive flu seasons between October 2015 and May 2018. Results: Seasonal influenza vaccine was administered to 315 chronically ill children in 3 consecutive flu seasons. During three seasons between October 1, 2015 and May 31, 2018, 12,690 chronically ill children were admitted to our center in the same diagnoses as children who were vaccinated. Of these 315 children, 87.0% had asthma, 4.4% had selective deficiency of immunoglobulin A, 2.2% had nephrotic syndrome, 1.6% had diabetes mellitus, 1.3% had cystic fibrosis, 1.3% were hematopoietic stem cell transplantation patients, 0.96% had cerebral palsy, 0.64% had Duchenne muscular dystrophy, and 0.6% had acute lymphoblastic leukemia. Conclusion: In this study, seasonal influenza vaccination rates of chronically ill children increased gradually in these 3 influenza seasons. However, the number is still low. It is clear that we need a plan to increase the vaccination rates of this patient group at our center.