To confirm the vertical transmission of Duck Enteritis Virus (DEV) from duck breeders to their ducklings, the authors have used methods of molecular biology tests (PCR alid RT-PCR). The result of investigation was confirmed to have the vertical transmission of DEV from infected duck breeders to their ducklings. This result was verified through clinical symptoms, disease characteristics and PCR tests (Hansen, 2000). 148 samples of one day old ducklings and dead embryos collecting from DEV infected Peking duck reproduction farm were tested by PCR techniques. Testing results indicated that DEV infected ratio varied from 0 to 4.6 percent by classical PCR technique, and from 79 to 97.3 percent by RT-PCR technique, with marking substance - SYBR Green Master Mix (Applied Bio Systems).