Objective: To evaluate cerebrospinal fl uid (CSF) patterns in Thai multiple sclerosis (MS) patients particularly oligoclonal bands compared with Western MS. Methods: Retrospective review of 72 patients from the MS Clinic, Siriraj Hospital, between January 1997 and June 2004. All were diagnosed MS using the Poser’ s criteria. Results: Seventy-six patients were evaluated. There were 62 female (86.1%),10 male (13.9%) with a female:male ratio of 6.2:1. The mean age at onset was 33.11±11.76 years. The mean duration of disease was 6.62 ± 5.9 years. Among the 56 MS patients, 52 patients (72.2%) had relapsing-remitting course, 3 (4.2%) had progressive relapsing course, 1(1.4%) had secondary progressive course, none had primary progressive course. Eleven patients (15.3%) had possible MS and the remaining 5 patients had Devic’s syndrome. Approximately 46% had CSF white blood cell (WBC) less than 5 cells/μL. Only 1 (2.3%) had CSF WBC count more than 50 cells/μL. However, both opticospinal form and classic form of MS similarly showed mononuclear cell predominant in differential CSF WBC count. Presence of CSF oligoclonal bands in defi nite MS patients was low in prevalence of only 27.3%. Conclusion: The CSF of Thai MS patients have lower incidence of oligoclonal bands compared with the reports from western countries.