- Background: A beneficial effect was observed in patients with psoriasis vulgaris following balneotherapy with Dead Sea bath salt. Objectives: To evaluate the possible role of trace elements in the effectiveness of balneotherapy. Methods: Serum levels of 11 trace elements were analyzed in 23 patients with psoriasis vulgaris who participated in a double-blind controlled study of balneotherapy with either Dead Sea bath salt (12 patients) or common salt (11 patients). Thirteen healthy volunteers served as controls. Results: The mean pre-treatment serum levels of boron, cadmium, lithium and rubidium were significantly lower in patients compared to controls, whereas the mean pre-treatment serum level of manganese was significantly higher in patients compared to controls. Balneotherapy with Dead Sea bath salt resulted in a significant decrease (P = 0.0051) in the mean serum level of manganese from 0.10 ′ 0.05 mol/L to 0.05 ′ 0.02 μmol/L. The mean reduction in the serum level of manganese differed significantly (P = 0.002) between responders (% Psoriasis Area and Severity Index score reduction > 25) and non-responders (% PASI score reduction < 25). Following balneotherapy with Dead Sea bath salt the mean serum level of lithium decreased in responders by 0.01 + 0.02 μmol/L, whereas its level in non-responders increased by 0.03 ′ 0.03 μmol/L. (P = 0.015). Conclusions: Manganese and lithium may play a role in the effectiveness of balneotherapy with Dead Sea bath salt for psoriasis.