Abstract: Monoclonal antibodies of anti-human T cell surface antigens, OKT3, OKT4 and OKT8 were used to determine the percentages of total T, T helper/inducer and T suppressor/cytoto-xic cells, and the ratios of OKT4⁺/OKT8⁺ cells in the peripheral blood of the patients with psoriasis vulugaris by direct immunofluorescent method. The patients were divided into 3 groups, active, resting and regressive stages. Each group consisted of 10 cases. Controls consisted of 10 healthy adults. Compared with the control group, no significant differences were found,in the percentages of OKT3⁺, OKT4⁺ and OKT8⁺ cells and the ratios of OKT4⁺/OKT8⁺ cells of the various stage groups (P > 0.05). It also showed no significant differences between the various stage groups (P > 0.05). Finally, the authors suggest that the quantitative abnormalities of T cells and their subpopulations, T suppressor and T helper cells may be secondary in the patients with psoriasis.