['Spontaneous tissue repair occurs in multiple sclerosis (MS), but the origin of remyelinating cells remains obscure. Here we explore the hypothesis that endogenous neural precursors are involved in MS disease processes.', 'We studied postmortem brain and spinal cord samples from MS patients using immunocytochemical techniques.', 'We show that cells co-positive for nestin and musashi-1 are not merely present in lesions, but found in markedly increased numbers (up to fivefold). Small numbers of nestin-positive cells show direct evidence of proliferation, co-staining for Ki67; some also coexpress glial fibrillary acidic protein or oligodendrocyte progenitor markers (NG-2 or PDGF-alpha receptor), or the early neuronal marker doublecortin, consistent with transition from neural precursors.'] Are disease-responsive neural precursor cells present in multiple sclerosis lesions?