Respiratory infections in chicken are seen worldwide but especially in temperate poultry-producing areas in winter months. There are many common viral diseases which can affect the respiratory system (air passages, lungs, air sacs) of poultry. Dust, ammonia and other gases, and other factors associated with poor ventilation, may act as predisposing factors. Morbidity is typically 10-20%, mortality 5- 10%. If condemned birds are included mortality may be more than 10%. Vaccination and Prevention:             Vaccination is the recommended method for prevention. Use of the mild live virus vaccines called as the B1and LaSota commonly done for prevention of the disease. The vaccines are applied into the nostril or eye or added to the drinking water or applied in the form of spray. Broiler chickens are usually vaccinated when seven to ten days of age. Chickens kept for egg production are usually vaccinated at least three times. The vaccine is given when birds are approximately seven days, again at about four weeks and a third time at about four months of age. Revaccination while in lay is commonly practiced. There is no treatment for Newcastle disease. Good management programs and good “biosecurity” measures may reduce the occurrence of Newcastle disease virus.