The immunoreactivity of tenascin, an extra cellular matrix glycoprotein, spatially and temporarily expressed in a site restricted manner during embryogenesis, wound healing and various benign and malignant tumours, was evaluated in 24 cases of adenoid basal cell carcinoma of the skin. The expression of tenascin showed three distinct patterns: firstly, the expression was confined to the stroma surrounding the tumour cells, secondly, to the stromal tissues of epithelial tumour foci and lumens of cribriform or cyst-like epithelial structures, and finally, a mixed pattern of these two was seen. It is suggested that in addition to the stromal reactivity, epithelial tumour cells may produce tenascin to deposit into the cribriform cystic lumens in the adenoid basal cell carcinoma in the skin.