Plasma concentrations of 8 proteins, including cytokines: interleukin-2 (IL-2), interleukin-6 (IL-6), interleukin-10 (IL-10), tumor necrosis factor-alpha (TNF-alpha), receptors: soluble IL-2 receptor (sIL-2R), p55 soluble TNF receptor (p55 sTNF-R) and acute phase proteins: alpha-2 macroglobulin (alpha-2 MG), C-reactive protein (CRP) were examined in 33 patients with drug-induced urticaria. The activity of selected proteins was measured using the immunoenzymatic ELISA method: a) in the acute stage of disease before treatment was administered, and b) after clearing of skin lesions, after treatment. In the acute stage of disease elevated concentrations of the examined proteins (p<0.001) in comparison to the control were found. After clearing of clinical symptoms the concentrations of IL-2, IL-6, p55TNF-R and alpha-2 MG were not significantly different from the control values. But despite deep decrease, slL-2R, IL-10, TNF-alpha and CRP levels were still significantly elevated (p<0.001) when compared to the control. Results of this study indicate complex character of pathogenic phenomena in drug-induced urticaria in which elevated activity of mediators acting as promotors and modulators of cellular immune response can be found.