The resurgence of dengue in Singapore since 1986 had been associated with an adult predominance and a very low incidence in children. No study had been carried out to investigate this finding. Here we report a serological study of 1068 children aged 0 to 15 years. There is a significant rise in seroconversion in children aged 6 years and older coinciding with the start of formal schooling. This suggests that there may be a change in the location where dengue is acquired.