Abstract: In order to cloning of the coding region of Tax gene of Bovine Leukosis Virus (BLV), PCR product of the open reading frame of the gene from BLV-FLK cell line and the buffy coat of infected cow were amplified by PCR. A 927 bp PCR product of the Tax gene with XhoI, BamHI restriction sites were subcloned of pCR 4-TOPO and digested by the mentioned endonucleases. Digested insert cloned in to pET-32(a) and transfected in E.coli cells. For the expression of Tax protein, the pET-32(a) recombinant vector was transformed and then induced in BL21 (DE3) strain of E.coli competent cells using IPTG, the presence of Tax expressed protein was shown in immunoblotting and SDS-PAGE system. With considering the significant prevalence of infection with BLV in Iran and the need for controlling the infection or disease through vaccination, the application of Tax recombinant protein for vaccine production is of great goals of this study in near future.