Genetic polymorphism of a bovine T-cell receptor beta gene was investigated by analysing restriction fragment length polymorphism (RFLP). One locus, denoted TCRB, with four allelic variants was revealed. The relationship between alleles at the TCRB locus and bull breeding values for disease and milk production was investigated in a sample of 196 progeny-tested AI bulls of the Swedish Red and White breed. The statistical evaluation of the data revealed no convincing association between TCRB alleles and any of the traits studied.