Affected 100 flocks revealed chronic whitish diarrhea. Consistent gross pathological lesions recorded were congestion and consolidation of lungs, hemorrhages in trachea, congestion and hemorrhages in liver, splenomegaly and necrotic foci on the kidneys, mortality in various flocks ranged from 3.7 – 15% detailed isolation and biochemical studies revealed that Ornithobacterium Rhinotracheale was responsible for this wide spread respiratory problem. Five ORT isolate positive PCR implications were pre elicited to be the size of 784 bp – finally it was confirmed that sequence analysis of 16 sr RNA and ORT isolates from Gen bank with identified from 94% to 98%. Antibacterial sensitivity revealed that most of the isolates were sensitive to lincospectin (lincomycin + spectinomycin) and doxycycline. Many of the isolates showed resistance to kanamycin, norfloxacin, enrofloxacin, tetracycline and chloramphenicol. Experimental infection of broiler orally with ORT evoked respiratory signs with mortality reached 20% lesions of moderated saculitis mild tracheitis and unilateral pneumonia were recorded during the observation period. On other hand of broiler infected with ORT revealed that the infected and treated broiler were lower significance than infected and treated with lincospectin. The microscopical examination revealed pathological changes can be seen in lung, trachea, liver, spleen and brain.