Although the dengue iceberg phenomenon is well known, there is a paucity of data on inapparent dengue. Results from a seroepidemiological study conducted during a dengue epidemic in 2007 in Singapore showed a seroprevalence of 65.9% and an inapparent dengue rate of 78%. Older adults (> 45 years old) had significantly higher rates of inapparent dengue infections (P < 0.05).