We evaluated CXCR3 expression on T-cells and levels of its ligand CXCL10 in blood and cerebrospinal fluid (CSF) of 22 patients with relapsing-remitting multiple sclerosis (RR-MS) in association with magnetic resonance imaging (MRI) disease activity. CXCL10 was strongly released intrathecally, but did not change in association with MRI activity. CXCR3 expression on T-cells was lower in the peripheral blood (PB) of RR-MS patients compared to healthy controls and was increased in the CSF of RR-MS patients undergoing acute attacks, as illustrated by Gd-enhancing lesions on MRI, compared to patients without enhancing lesion. Our results suggest that MRI-documented disease activity is associated with an increase of CXCR3 positive T-cells in the CSF, possibly due to the migration of activated T-cells from the circulation into the CSF.