This study was carried out to determine the rate of Theileria infection in cattle and camels in Behera governorate by microscopic examination, confirm and identify the species by polymerase chain reaction (PCR). The prevalence of Theileria infection in cattle and camels was 20% (15/75) and 28% (21/75) respectively, by microscopic examination (ME) of blood smears. Five positive samples by ME (3camels and 2 cattle) in addition, four negative samples were subjected to semi-nested PCR. The PCR result (6 out of 9) examined blood samples (4 camels and 2 cattle) were PCR positive using Theileria species specific primer at 430bp. All positive samples for Theileria sp. Using Tbs-S/Tbs-A primers were used as a template and amplified by using Ta-S/ Tbs-A primers specific for Theileria annulata. All examined samples (6/6), 2 from cattle and 4 from camels were positive for Theileria annulata at 193 bp. In conclusion, the PCR especially semi-nested PCR (snPCR) are highly specific and sensitive methods for identifying the species of Theileria annulata and screening the carrier cattle and camels in the epidemiological surveys. On the other hand, Giemsa staining method is not suitable for detecting the carrier or chronic phases of theileriosis, although it is an easy and fast diagnostic technique for detecting this infection in acute phase with clinical signs.