Myelin proteins, including myelin basic protein (MBP), proteolipid protein (PLP) and myelin oligodendrocyte glycoprotein (MOG) are candidate autoantigens in MS. It is not clear whether MS patients show a predominant reactivity to one or several myelin antigens. We evaluated the IFN‐γ production induced by MBP and MOG and selected MBP‐, MOG‐ and PLP‐peptides in MS patients and healthy controls using the IFN‐γ ELISPOT assay. Most MS patients and healthy controls showed a heterogeneous anti‐myelin T‐cell reactivity. Interestingly in MS patients a positive correlation was found between the anti‐MOG and anti‐MBP T‐cell responses. No myelin peptide was preferentially recognized among the peptides tested (MBP 84–102, 143–168, MOG 1–22, 34–56, 64–86, 74–96, PLP 41–58, 184–199, 190–209). In addition the frequency of IL2R⁺ MBP reactive T‐cells was significantly increased in blood of MS patients as compared with healthy subjects, indicating that MBP reactive T‐cells exist in an in vivo activated state in MS patients. Most of the anti‐MBP T‐cells were of the Th1‐type because reactivity was observed in IFN‐γ but not in IL‐4 ELISPOT‐assays. Using Th1 (IL‐12) and Th2 (IL‐4) promoting conditions we observed that the cytokine secretion pattern of anti‐MBP T‐cells still is susceptible to alteration. Our data further indicate that precursor frequency analysis of myelin reactive T‐cells by proliferation‐based assays may underestimate the true frequency of myelin specific T‐cells significantly. J. Neurosci. Res. 63:290–302, 2001. © 2001 Wiley‐Liss, Inc.