T-cell accumulation in the central nervous system (CNS) is considered crucial to the pathogenesis of multiple sclerosis (MS). We found that the majority of T cells within the cerebrospinal fluid (CSF) compartment expressed the CXC chemokine receptor 3 (CXCR), independent of CNS inflammation. Quantitative immunohistochemistry revealed continuous accumulation of CXCR3+ T cells during MS lesion formation. The expression of one CXCR3 ligand, interferon (IFN)-gamma-inducible protein of 10 kDa (IP-10)/CXC chemokine ligand (CXCL) 10 was elevated in MS CSF, spatially associated with demyelination in CNS tissue sections and correlated tightly with CXCR3 expression. These data suggest a critical role for CXCL10 and CXCR3 in the accumulation of T cells in the CNS of MS patients.