Bovine respiratory disease (BRD) caused by various Mycoplasma, other bacteria or fungi is a major health problem of cattle worldwide. The present study was conducted to examine 100 nasal swabs of cattle (1-5 years ) reared in private farms at El-Menoufea governorate showing Symptoms of depression , reduced feed intake, respiratory problems, dyspnea with or without nasal discharge and pneumonia. 50 lung tissues collected from different abattoirs at El- Menoufia Governorate and obtained from part showing pneumonia.
 Mycoplasma bovis, Pasteurella multocida and Mannhiema haemolytica were isolated in percentages of (8%, 18% and 12%) and (6%, 14% and 10%) in both nasal swabs and lung tissues respectively. The main isolated moulds and yeasts, were Asperigullus  fumigatus, Asperigullus  niger, Asperigullus  candidus, Asperigullus  flavus, Penicillum sp < /em>. and Candida sp < /em>. which were isolated in percentages (16% , 72% , 16%, 8% , 32% and48% ) and (8% , 8% , 0% ,8% , 24% and 40%) in both nasal swabs and lung tissues respectively. Polymerase chain reaction (PCR) is very specific, simple, sensitive and rapid diagnosis of Mycoplasma bovis, Pasteurella multocida, Asperigullus fumigatus, A Asperigullus niger, Asperigullus flavus and Candida species.  Pasteurella sp. isolates were sensitive to Tulthromycin and Gentamicine antimicrobials while M. haemolytica isolateswere sensitive to Tulthromycin (Draxxin)  Nevertheless, Mycoplasma bovis isolates were sensitive to Tulthromycin (Draxxin)   and Ciprofloxacin