Background: Multiple Sclerosis (MS) has two pathophysiological processes, one is inflammatory and the other is degenerative. We searched the relation between inflammatory biomarkers within the serums of patients who have active lesions in neuroimaging, and the existence, number, and localization of active lesions, as an indicator of the inflammatory process. Also, regardless of the imaging, we aim to detect the inflammatory period in which clinical, radiological follow-up, and disease-modifying treatments are effective with serum parameters.Methods: One hundred eighty six MS patients, presented to our hospital between January 2016 to November 2021 and 94 age-and- sex-matched healthy volunteers were recruited for our study. While 99 patients had active lesions in magnetic resonance imaging, 87 patients didn’t have any active lesion. Neutrophil/lymphocyte (NLR), platelet/lymphocyte (PLR), monocyte/lymphocyte (MLR) ratios were determined. SII (systemic immune inflammatory index) value was calculated according to the platelet X neutrophil/lymphocyte ratio formula.Results: NLR, MLR and especially PLR, SII ratios were found to be statistically highest in the patient group with active lesions. According to the presence of active lesions, cut-off values for MLR, PLR, NLR and SII were respectively 0.18, 1.53 and 117.15, 434.45.Conclusions: We found that SII and PLR values were correlated with radiological activity. As easily accessible, inexpensive markers, SII and PLR can detect the inflammatory period in which patients have a higher response to treatment, with sufficient sensitivity and specificity. It can also be a helpful evaluation candidate for the presence of radiological activity.