During the last decade Martinique experienced four dengue epidemics, each characterized by the predominance of 1 or 2 serotypes. In this retrospective database analysis, we investigated the relationship between dengue serotype and disease severity. Data on dengue were collected from 715 patients (male/female ratio 0.87), 14 to 91 years of age (median 35 years) examined in the adult emergency department between 2005 and 2010. In this series, DENV-4 infections more frequently had a milder clinical presentation. The DENV-2 infections were most often secondary infections admitted at the critical phase of dengue illness with signs of plasma leakage. The DENV-1 infections were disabling, particularly in females, and most often led to disease of intermediate severity, without overt plasma leakage. These data were consistent with there being differences in virulence between serotypes, regardless of the host's immune status. However, secondary DENV-2 infections showed an increased risk of plasma leakage. (R.A.)