To investigate the role of T cells in psoriasis, we analyzed the T-cell receptor (TCR) repertoire in peripheral blood lymphocytes (PBLs) and in skin lesions of 9 patients with chronic plaque-stage psoriasis by means of immunohistochemistry. An extended panel of monoclonal antibodies detecting 11 different V beta families was employed in this study. In the peripheral blood, no predominant TCR V beta expression was detected and interindividual differences were small. Skin-infiltrating T cells showed only marginal differences in the TCR V beta usage when compared with PBLs. However, in 3 patients the intraepidermal infiltrate comprised up to 40% of T cells expressing a TCR V beta region which was virtually absent in the peripheral blood and the dermal infiltrate. Thus, although the TCR V beta usage of skin-infiltrating T cells showed little difference compared to PBLs, several cases exhibited a significant increase of epidermotrophic T cells using one particular V beta region.