Dengue is endemic in almost all provinces in Indonesia and it cause health problems with outbreaks in many cities and rural areas. Based on the Ministry of Health data in 2015, there were 126,675 dengue fever patients recorded in 34 provinces and 1,229 among them were fatal. This study is aimed to determine the exposure of most vulnerable groups i.e. children against dengue virus and to assess the risk factors. The study was conducted using Preserved Biological Material (BBT) from National Basic Health Research (Riskesdas) 2013 on healthy population of high-risk group, i.e., children in urban areas from 27 provinces. Serological investigation carried out by IgG indirect ELISA method on 1766 samples and 1633 were analyzed. The average of dengue IgG seropositivity in children under-fives (12-59 months) sera against dengue virus is 51.9%, while in children (5-14 years) were higher at 74.6%. This numbers are indicating that about 2/3 of the children in the urban areas have been infected by at least one of the dengue viruses. The risk factors of no repellent use, and refrigerator ownership revealed as major determinants for the infection. Considering that Indonesia has suitable climate for dengue vector breeding, it is important to increase public awareness to keep the environment clean.