To carry out the immunological experiments on the serum of Multiple Sclerosis (MS) patients, based on a correlation between Borrelia burgdorferi infection and contracting MS autoimmune disease the outer surface protein D (OspD) of the bacterium was expressed and purified. A clone containing the OspD gene in pET11a expression vector under the control of T7 promoter was transformed to the bacterial host BL21 (DE3). Some of the colonies were selected for IPTG-induced expression. The colony with the highest amount of OspD was selected for large-scale expression. Large-scale protein purification was performed by the reversed phase HPLC with a C4 preparative column; ultimately, the expressed purified protein was confirmed by the Western blot technique.