Background: To date, although great effort has been made to identify biomarkers of multiple sclerosis (MS), it remains unclear whether lysophosphatidic acid (LPA) can be used as a biomarker for MS.Methods: This study compared the LPA levels in the serum and cerebrospinal fluid (CSF) in patients with MS in relapse versus in remission and investigated the change in LPA levels in MS patients in relapse after treatment. Forty-one patients with relapsing-remitting MS (RRMS) (21 patients in relapse and 20 patients in remission) and 21 patients with non-inflammatory, non-vascular neurological diseases as controls were included in this study. MS patients in relapse received standard glucocorticoid treatment. LPA concentrations in serum and CSF were measured using an inorganic phosphate quantification assay.Results: LPA levels in the serum and CSF were significantly higher in MS patients in relapse than in MS patients in remission and control patients (P < 0.05). The LPA level in MS patients in relapse was significantly reduced after treatment (P < 0.05).Conclusion: LPA concentrations in the serum and CSF may be used as biomarkers to monitor disease activity and therapeutic response in MS patients.