Immunoregulatory conditions in atopic dermatitis (AD) involve both Th1 and Th2, although primarily Th2. The suppressor of cytokine signalling 3 (SOCS3) may mediate Th2 regulatory response through negative regulation of Th1 pathways. We examined SOCS3 expression in skin lesions of patients with severe AD and compared it with that in patients with the Th1 disorder, psoriasis. We assessed SOCS3 expression in skin lesions from seven patients with severe AD and five patients with typical psoriasis, and in skin from three normal subjects, using immunohistochemical staining, in situ hybridization and reverse transcription PCR. Strong SOCS3 expression was found in skin lesions in all patients with AD, but only weak expression in patients with psoriasis and in normal subjects. Overexpression of SOCS3 is prominent in the skin of patients with severe AD and consequently may prove useful for evaluating the severity of AD as a Th2-dominant condition.