Abstract: Morphogenesis of duck enteritis virus CH virulent isolate (DEV-CHv) was investigated by ultrathin sectioning and transmission electron microscopy of infected duck embryo fibroblasts (DEF). Attached DEV-CHv probably penetrated the DEF cell membrane by direct fusion between the viral envelop and the plasma membrane. Progeny nucleocapsids assembled in the nucleus and exited from this compartment into the cytoplasm by budding through the inner nuclear leaflet into the interconnected perinuclear cisterna and cisternae of endoplasmic reticulum. DEV tegumentation occurred in cisternae of endoplasmic reticulum and the tegumented progeny nucleocapsids obtained their final envelop by budding into cytoplasmic vesicles. Intravesicular mature DEV-CHv particles were discharged from the cell through exocytosis of the cytoplasmic vesicles by DEF, or through rupture of the virus-containing vesicles.