The epidemiology, Pathogencity and the possible ways of treatment of Klebsiella pneumoniae (K. pneumoniae) infection as a respiratory pathogen in broiler chicken farms in different places in Gharbia Goernorate were investigated during 2014/2017.For this purpose 150 samples were collected from lung, trachea, , liver and intestine samples of 150 diseased, 1-5-week-old commercial broiler chickens suffered from respiratory disorders, diarrhea, growth retardation and mortality with pneumonia, pericarditis, airsaculitis and enlarged liver. Bacteriological examination of swabs from trachea, lung, liver and intestine revealed Gram negative, non-motile rod-shaped organisms which were commonly isolated from lung, liver, intestine and trachea. The isolation trials revealed 10 K. pneumoniae positive cases with an incidence (6.6%). Identification of the isolated strains Biochemically by API 20 E and molecularly by polymerase chain reaction (PCR) revealed that the isolates belonged to K. pneumoniae. The K. Pneumoniae isolate was inoculated experimentally in 7 day-old chicks and clinical signs, lesion were reproduced. Clinical signs& P.M lesions characteristic in K.Pneumoniae infection was reproduced when the K. Pneumoniae isolates was inoculated in 7 day old chicks. K.Pneumoniae was also reisolated. Clinicopathological features and re-isolation of the organism from experimentally infected chicks were recorded. The results of the in vitro antibiotic sensitivity test revealed that the isolated strains were highly sensitive to gentamycin, amikacin, sulphamethoxazole–trimethoprime, ciprofloxacin and chloramphenicol, considerably sensitive to kanamycin, norfloxacin, oxytetracyclin and neomycin but resistant to Ampicillin and Erythromycin. The clinical signs, post-mortem findings and the histopathological lesions of tissue sections from different organs of experimentally infected chickens were less severe after treatment with gentamycin, amikacin combined with sulphamethoxazole–trimethoprime in drinking water for 3 consecutive days.