Dengue virus (DENV) is the cause of dengue illness (dengue fever, dengue hemorrhagic fever, and dengue shock syndrome). CDC researchers have developed a RT-PCR multiplex assay that, prior to sero-conversion, selectively detects dengue virus in biological or other fluid media, such as whole blood, plasma, or serum. The primers and probes from this assay are sufficiently specific to amplify and detect all four DENV serotypes. This FDA-approved technology may provide an improved method for rapid and accurate serotyping of dengue virus in clinical and research settings.