Respiratory tract diseases represent a major causes of economic loss of sheep. This study was planned to know some light on respiratory viral infection in sheep. A total of 300 sheep serum samples were collect- ed from 2 Egyptian Governorate (Kafer El-Sheikh and Alexandria). The collected sera represented age varied from (3-12 months). These samples     were tested serologically by Enzyme Linked Immunosorbent Assay "ELISA" Technique and Serum Neutralization Test "SNT" for detecting specific antibodies of parainfluenza virus type 3 (PI- 3), infectious bovine rhinotracheitis virus (IBR) and adenoviruses. Serological examination revealed the presence of specific antibodies against    respiratory viruses used. Out of 300 sheep serum samples (7.8%16.2% and 17.2%) for IBR, PI-3, enovirus respectively were detected by ELISA. While, they were 3.9%, 1 1.0% and 9.3% respectively by SNT.