Deposits of immunoglobulins (Igs) and complement components can be demonstrated in the stratum corneum (SC) of psoriatic lesions by immunofluorescent (IF) technique. In this paper, the underlying inflammation in the lesional dermis, which may affect the immune reactions in the SC, was investigated by immunocytochemical and IF techniques.Using the reactive tests for a-naphthyl acetate esterase (ANAE) activity, T-Iymphocytes were found to be predominant among inOammatory infiltrates in the lesional dermis. By the immunoperoidase method, IgA and secretory component (S-component) bearing cells, which seemed to be bound to each other on their cell surfaces, comprised about 20% of the mass of infiltrates in the upper dermis of early psoriatic lesions. These Igs and S-component bearing cells seemed to be non T -lymphocytes, The inflammatory conditions in the dermis appeared to be closely connected to the immune reactions in the SC of psoriasis.