Infectious bronchitis, Newcastle disease, infectious laryngotracheitis, avian influenza, and pneumovirus are the viruses that more frequently affect the respiratory tract of chickens, because of their tendency to change its antigenic properties Infectious laryngotracheitis has appeared in the broiler industry as a serious disease. Newcastle is a highly contagious, disease in which all birds in a flock usually become infected within three to four days. Avian pox is a relatively slow-spreading viral disease in birds, characterized by wart-like nodules on the skin and diphtheritic necrotic membranes lining the mouth and upper respiratory system. In spite of regular vaccination of chicken flocks in Egypt with Infectious Bronchitis virus (IBV) vaccine, respiratory and kidney lesions had developed. Sporadic outbreaks of avian influenza were reported in several countries .In general, the highly pathogenic forms of these diseases are easily diagnosed mainly because of the high mortality and typical lesions observed. Pneumo viruses are now widely distributed in the poultry industry, causing “swollen head syndromes," which is a term used to describe the condition in chickens. Vaccination programs are constantly adjusted to improve protection against diseases. Improved vaccines are needed to control the diseases.