Two natural outbreaks of infectious laryngotracheitis (ILT) were diagnosed for the first time in 3-4-week-old broiler chickens in western area of Saudia Arabia. The morbidity and mortality rates as well as the characteristic clinical signs and postmortem lesions were described. The specific intranuclear inclusion bodies were detected in direct Giemsa stained tracheal smears and formalin fixed tracheal tissue sections. The virus was isolated on chorioallantoic membrane (CAM) of chicken embryo which produced typical plaques on CAM & embryo deaths, then identified serologically by agar gel precipitation test. Histopathological examination of naturally infected tracheal tissues were described. Comparison of pathogenicity between ILT field virus isolates in
chicken embryos was reported.