The pathogenic role of myelin basic protein (MBP)-specific T lymphocytes in multiple sclerosis (MS) has been suggested by the encephalitogenicity of MBP-specific T cells in experimental allergic encephalomyelitis (EAE). In humans, extensive analysis of TCRs involved in MBP recognition has led to conflicting results, varying from an intra- and/or interindividual restriction to high diversity in TCRAV/TCRBV gene usage. We previously established MBP-specific T cell lines (TCLs) from healthy monozygous twins and characterized their fine epitope specificity. In this study, we report on the TCR alpha beta gene usage of 52 of these MBP TCLs that are specific for epitopes recognized by both co-twins within the same pair. High overall diversity in the TCR alpha and TCR beta genes used for recognition of this self-Ag, MBP, was observed. Variable genes belonging to 19 different TCRAV and 16 different TCRBV subfamilies are expressed by the 52 TCLs herein studied. In co-twins, TCLs utilized genes belonging to common TCRAV and/or TCRBV gene subfamilies in 7 of 13 instances of shared epitope recognition. Statistical analysis of intrapair concordance for TCR gene usage for the recognition of a given peptide did not show any significant deviation from values that would be anticipated in the absence of genetic background effect.