Abstract: One hundred patients with psoriasis were detected for lymphocyte types (T. B. N. D. cells) in their peripheral blood by mixed rosette forming cell test. The 19 of them were sampled at random. The ABC stain of immunoenzymatic technique with monoclonal antibody Leu system was used to observe the subsets of the T-cells. It was found that there was an apparent fall in the percentage of T cells (P < 0.001), an increase in the percentage of Ts cells (2a) (P < 0.05), a marked fall in the percentage of TH cells (3a) and 3a/2a (P < 0.05), and an increase in the percentage of the R, N, and D cells (P < 0.05) as compared with those of normal persons.