Plasma concentrations of interleukin-10 (IL-10) were examined in 126 patients with drug-induced cutaneous reactions: maculopapular eruptions (ME), erythema multiforme (EM), erythema multiforme coexisting with erythema nodosum (EMN), drug-induced urticaria (DU), hyperergic vasculitis (HV), Stevens-Johnson syndrome and toxic epidermal necrolysis (SJS/TEN). Activity of the cytokine 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 highly elevated mean concentrations of IL-10 in all 6 groups of patients were found (p<0.001) in comparison with the control. After clearing of clinical symptoms IL-10 concentrations were decreased highly significantly (ME, EM, DU, HV) or significantly (EMN, SJS/TEN) in comparison with the values before treatment, but remained still considerably elevated (p<0.001; p<0.01) when compared with the healthy control. Results of this study indicate that the compensatory antiinflammatory response, expressed as elevated IL-10 activity, is induced as early as in the acute stage of skin lesions and lasts longer than clinical symptoms of drug-induced cutaneous reactions.