This study presents an immunohistochemical characterization of somatostatin-positive dendritic cells in psoriatic lesions. Somatostatin is a neuropeptide with inhibitory action on several neuropeptides and hormones, but also with immunomodulating properties, and has been used in several studies as treatment for psoriasis. The number of somatostatin-positive dendritic cells was found to be larger in psoriatic lesions than in normal skin of psoriasis patients and healthy controls. Colocalization of somatostatin and HLA-DR immunoreactivity was demonstrated in a subgroup of dendritic cells of psoriatic skin, whereas double-labelled cells were not found in uninvolved skin. The somatostatin-positive cells in the epidermis and dermis did not co-express CD1a, CD35, CD45RB, CD45RO, CD68, factor XIIIa or S-100. On the basis of these findings, the somatostatin-positive cells seem to represent a specific population of dermal dendritic cells, distinct from Langerhans' cells and factor XIIIa-positive cells, which are found in elevated amounts in chronic plaque psoriasis.