A real-time PCR assay, which enables simultaneous detection and differentiation of all three serotypes of Marek's disease virus, without the need for post-PCR sequencing, has been developed. The assay is based on the primer-probe energy transfer real-time PCR, which has a relatively high tolerance towards point mutations in the probe region. The PCR is followed by a probe melting point analysis, which enables confirmation of identity of amplicon and differentiation of serotypes. The assay targets the MDV031 gene, encoding UL19 major capsid protein-like protein and was shown to be quantitative, with a detection limit below 10 TCID50/ml starting material. This sensitivity is similar to the one obtained with traditional virus cultivation. However, the PCR method can provide a laboratory result within a day, while the virus cultivation method takes more than a week to perform. The new method will be useful for testing of avian live viral vaccines and screening for extraneous agents.