Bluetongue is an infectious disease that primarily affects sheep. But due to serious socioeconomic consequence of it outbreaks on the international trade it has been included in the OIE notifiable diseases (list A). During 2007-8, total number of 130 blood samples gathered from suspected sheep to bluetongue disease in seropositive region including Khuzestan, Kurdistan, Fars, Ilam and Qum provinces. Blue tongue viruses were diagnosed in some animals by RT-PCR and nested PCR, by targeting S7 segment. This genome segment was sequenced and analyzed in 11 samples as a conserved gene in BTV serogroup. The phylogenetic evaluation showed that there were two distinct clusters. One cluster was significantly near to East BTV strains from China and India and also was classified with BTV9/16 from Turkey. The second group was very similar to West BTV strains from US, Africa and Europe. This cluster was categorized with BTV4 from Turkey.