The purpose of this study was to investigate and to compare, by in situ hybridization, gene expression of IL-1 beta, IL-8, TGF-beta 1, TGF-beta 2, TGF-beta 3, TGF-alpha, p53 and c-myc in lesions and in non-involved skin of patients with psoriasis. All lesional skin biopsies showed overexpression of IL-1 beta, IL-8 TGF-alpha mRNAs. IL-1 beta hybridization signals were strong in a small number of cells localized predominantly in the dermal papillae and in the suprapapillary epidermis. Overexpression of TGF-alpha was observed in all suprabasal keratinocytes, whereas strongly elevated IL-8 mRNA expression was found to be restricted to clusters of suprabasal keratinocytes. TGF-beta 3, p53 and c-myc transcripts were clearly detected in the epidermis of all biopsies, although expression levels were comparable in lesional and non-lesional skin.