Aim: The aim was to investigate the infectious conditions of Epstein-Barr virus (EBV) in patients with multiple sclerosis (MS). Methods: Cerebrospinal fluid (CSF) of 20 patients with MS and 20 with other neurological diseases (OND) were tested with indirect immunofluorescence for anti-EBV capsid antigen (EBV-CA) immunoglobulin G (IgG), IgG affinity for anti-EBV-CA, anti-EBV-CA immunoglobulin M (IgM), anti-EBV early antigen (EBV-EA) IgG and anti-EBV nuclear antigen (EBNA) IgG. According to the pattern of antibodies in CSF, infection rates of acute, chronic, primary, recurrent, and past infections were analyzed in the two groups of patients. Results: There were no significant differences in anti-EBV-CA, anti-EBC-EA, and anti-EBNA antigen IgG in CSF between MS and OND patients ( P > 0.05). The positive rate of low affinity for anti-EBV-CA IgG in MS patients was significantly higher than that for OND patients (75% vs . 40%, P vs . 25%, P P Conclusion: Acute infection of EBV closely correlates with the occurrence of MS.