Multiple sclerosis (MS) has been associated with particular HLA haplotypes and has recently been reported to also be associated with the T cell receptor (TCR) beta-chain complex. We have tried to determine the source of the TCR-beta/MS association by exploiting the pattern of linkage disequilibrium within the TCR-beta complex. We describe a new DNA polymorphism with the TCR variable region gene segment V beta 15 which appears to localize between the constant region and V beta 11. When the distribution of V beta 11-V beta 15 haplotypes in MS patients was compared to healthy controls, the strength of the V beta 11-V beta 15 MS association (p = 0.107) was much less than the MS association with the adjacent V beta 8-V beta 11 haplotype (p = 0.0010). On the basis we exclude an MS susceptibility gene telomeric to V beta 11. The reported MS association with the TCR-beta gene complex therefore does not appear to be due to genes within the diversity, joining, or constant region but more likely involves a specific gene(s) within the variable region.