The concentration and distribution of total mRNA is thought to reflect cellular activity. To clarify the distribution of total mRNA in normal and psoriatic human skin, in situ hybridization with a digoxigenin-labeled poly(dT) probe was carried out. In normal skin, polyadenylated RNA was distributed uniformly throughout the epidermis, including the basal, spinous, and granular layers. The nucleus and cytoplasm of skin appendages were stained more strongly than those of epidermal cells. The concentration of total mRNA in the epidermis of psoriatic skin was thought to be increased because of strong staining, especially in the basal layer, compared with that in normal epidermis, possibly reflecting hyperproliferation of keratinocytes. Results suggest that in situ hybridization with a poly(dT) probe is a useful strategy to study total mRNA distribution in human skin.