Babesiosis is a major problem in small ruminants caused by Babesia spp. There are many reports on high prevalence of Babesiosis from different parts of Iran. This study was performed to identify the Babesia species in blood samples of clinically suspected sheep in Tabriz, northern west of Iran. Blood samples from 50 sheep with suspected clinical Babesiosis assessed by semi nested PCR method using specific primers of Babesia to amplify a 186 bp part of 18ssrRNA gene of the parasite. Nine out of 50 samples (18%) assessed by PCR using specific primers PA and PB showed bands about 400-420 bp agree to Babesia or Theileria parasites. By Semi-Nested PCR using species-specific primers of B. Ovis and B. motasi, Seven out of 9 samples (14%) that were positive in primary PCR showed a 186 bp band agree to B. ovis with specific primers of B. ovis. We found no B. motasi cases using B. motasi specific primers. High prevalence of Babesia ovis in sheep and goat has been reported from Northeast of Iran. We found the PCR-based diagnosis assay is applicable to detection the B. ovis. Based on the results of our study and other related findings, it can be say that B. ovis could be considered as a main causative agent of sheep babesiosis in East Azerbaijan. High frequency of babesiosis in ruminants in East Azerbaijan province and other parts of Iran shows the priority of planning to control the disease in animals and human in national and provincial levels.