T cell responses to the immunodominant peptide (residues 83–99) of myelin basic protein are potentially associated with multiple sclerosis (MS). This study was undertaken to examine whether a common sequence motif (s) exists within the TCR complementarity-determining region (CDR)-3 of T cells recognizing the MBP83–99 peptide. Twenty MBP83–99-reactive T cell clones derived from patients with MS were analyzed for CDR3 sequences, which revealed several shared motifs. Some Vβ13. 1 T cell clones derived from different patients with MS were found to contain an identical CDR3 motif, Vβ13. 1-LGRAGLTY. Oligonucleotides complementary to the shared CDR3 motifs were used as specific probes to detect identical target CDR3 sequences in a large panel of T cell lines reactive to MBP83–99 and unprimed PBMC. The results revealed that, in contrast to other CDR3 motifs examined, the LGRAGLTY motif was common to T cells recognizing the MBP83–99 peptide, as evident by its expression in the majority of MBP83–99-reactive T cell lines (36/44) and PBMC specimens (15/48) obtained from randomly selected MS patients. The motif was also detected in lower expression in some PBMC specimens from healthy individuals, suggesting the presence of low precursor frequency of T cells expressing this motif in healthy individuals. This study provides new evidence indicating that the identified LGRAGLTY motif is preferentially expressed in MBP83–99-reactive T cells. The findings have important implications in monitoring and targeting MBP83–99-reactive T cells in MS.