Introduction: To investigate the role of borrelia infections in pathogenesis of multiple sclerosis (MS) the presence of antibody against Borrelia persica (the most common species of borrelia in Iran) in the serum and CSF of MS patients was studied. Material and Methods: The presence of antibodies against Borrelia persica antigens was studied in the serum and CSF of 50 MS patients and 30 age and sex matched normal controls by immunoblotting. The two most important surface lipoproteins of Borrelia burgdorferi (OspA & OspD), which were produced by recombinant technology, were also included in the study. Results: The obtained results showed that 33 of 50 patients who were tested and some of normal controls, had antibodies in their serum against Borrelia protein bands. Fisher’s exact test indicated a significant difference between MS patients and normal controls regarding 43 KDa protein band, which became positive in 7 MS patient but none of our controls. We could not detect positive reaction with Borrelia surface lipoproteins (OspA & OspD) in serum and CSF of any of our patients or normal controls. Conclusion: Considering our results and a lot of similarities between pathogenesis and clinical manifestation of MS and spirochetal lyme disease there are some evidences for spirochetal basis of MS but its confirmation needs further investigations.