A method for detection of Infectious Bursal Disease Virus (IBDV) based upon the reverse transcription polymerase chain reaction, or RT-PCR has been developed. The obtained amplified DNA fragments from IBDV vaccine strains and field isolates have been analyzed by digestion with EcoRII, MboI, SspI, BspMI, SacI restriction endonucleases. The restriction analysis of obtained amplicons is able to differentiate IBDV vaccine strains and very virulent field isolates