Nickel allergy is manifested as contact allergic eczema elicited by delayed-type hypersensitivity, the reaction being mediated by T lymphocytes. We examined the T-cell receptor (TCR) beta-chain variable gene segment (Vbeta) use of nickel-induced CD4+ and CD8+ T cells in the peripheral blood of nickel-sensitive and nonsensitized subjects. The results show that each patient had an individual Vbeta repertoire overexpressed, these being in CD4+ cells Vbeta10 and Vbeta13 (in subject A); Vbeta1, Vbeta2, Vbeta13 and Vbeta21 (subject B); Vbeta1 and Vbeta10 (subject C); Vbeta9 and Vbeta19 (subject D). Thus, no single Vbeta gene dominated in a majority of the CD4+ samples. The Vbeta genes overexpressed in patient CD8+ nickel-induced T cells were Vbeta1 (in subject A), Vbeta1 (subject B), Vbeta1 and Vbeta2 (subject C) and Vbeta7 (subject D), domination of Vbeta1 being seen in most of the CD8+ samples (75%). No specific overexpression of any Vbeta genes in the nickel-allergic subjects was found in comparison with the non-sensitized subjects. In conclusion, an individual pattern of restricted Vbeta genes was induced with nickel in CD4+ and CD8+ T cells in each nickel allergy patient.