Dengue is an acute viral disease transmitted by the Aedes aegypti and Aedes albopictus mosquito, which are present in most tropical urban areas of the world. There are four antigenically distinct serotypes, designated dengue-1 (DEN-1), dengue-2 (DEN-2), dengue-3 (DEN-3) and dengue-4 (DEN-4). Dengue outbreaks have occurred in several regions in Asia, involving four serotypes of dengue 1, 2, 3 and 4. In review of the few cases of dual infection documented in the literature, we report here a case of simultaneous infection with DEN-2 and DEN-3 in a Chinese patient return from Sri Lanka. The dual infection was identified by type-specific indirect immunofluorescence assay and confirmed by reverse transcriptase-polymerase chain reaction (RT-PCR) and sequence determination. This is the first documented case of simultaneous infection with serotype of DEN-2 and DEN-3 in China.