Background:  Influenza A/H1N1, A/H3N2 and B/Yamagata and B/Victoria viruses have circulated and caused disease in humans on a global basis since 1977. Those influenza viruses can cause seasonal epidemics upper respiratory tract infections. The aim of study to determine serologic prevalence of seasonal influenza viruses in children.                                                                                               Method:. This is a cross-sectional serological study. Serum samples were collected from Clinical trial of Biofarma influenza vaccine on October 2017 to June 2018 in Bandung, West Java, Indonesia. Antibody titers were measured by hemagglutination inhibition (HI) assay. Serologic prevalence was calculated based on the results of HI assay (positive, HI titer > 1:40).                                                                                                                    Results: A total of 630 serum samples had been collected from unprimed healthy children age of 6 months to 18 years old. The seroprevalence rate of A/H1N1, A/H3N2, B/Victoria and B/Yamagata were 61%, 70.2%, 32.9%, and 41.0%, respectively. Based on the age specific group I (6 – 36 months), II (3 – 8 years), III (9 – 12 years), IV (13–18 years), the seroprevalence rate of A/H1N1 (22.2, 70.4, 78.3, 65.6), A/H3N2 (34.1, 82.2, 74.4, 83.9) B/Yamagata (21.5, 31.1, 45.6, 30.0), and B/Victoria (5.2, 34.8, 50.0, 63.3). The seroprevalence rate of A/H3N2 was higher than the others.                                         Conclusion: The seroprevalence rate of all age group are below 85% and  trend to increase as older age. Influenza vaccination is needed for children since age of 6 months old.