White blood cell picture of the peripheral blood was determined in 37 patients with psoriasis vulgaris treated with PUVA and cignoline. The studies were performed during active period of the disease, during its treatment and in the initial period of the remission. The results were compared with those obtained in 20 healthy age-matched persons and they were correlated with the skin surface area involved, duration of the diseases and duration of its latest relapse. In the active period of the disease per cent of peripheral blood neutrophils and basophils is significantly increased, while per cent of lymphocytes is lowered. Increased per cent of neutrophils positively correlates with the skin surface area involvement.