Among the therapeutical modes of psoriasis, sea-water baths with salts from the Dead Sea in combination with ultraviolet light (Tomesa therapy) play an important part. In a previous paper, we showed that treatment of isolated murine skin with Tomesa salt solutions resulted in an irreversible decrease of ATPase-positive epidermal Langerhans' cells. Our present study is concerned with the treatment of healthy persons and psoriasis patients with baths containing Tomesa salts, which lead to reduced amounts of detectable Langerhans' cells in the epidermis, as well. Baths containing sodium chloride in comparable concentrations, however, were without effect at all. Our findings demonstrate that the antipsoriatic activity of Tomesa therapy is not only due to physical effects but may also be the result of definable pharmacological actions of the salts on skin cells.