The fibrinolytic activity of normal human oral epithelium and abdominal epidermis was studied by two techniques. With fibrinolytic autography, dorsal tongue, ventral tongue, cheek, palate and gingival sulcus epithelium showed fibrinolytic activity but oral gingival epithelium and the epidermis showed no activity. With a fibrin plate technique, potassium thiocyanate extracts of epidermis and oral epithelium all showed strong fibrinolytic activity, but activity in tris buffer extracts was demonstrable only with oral epithelium, and the activity was much weaker. The fact that the tris buffer extractable fibrinolytic activator was demonstrated only in oral epithelium suggests that the presence of this activator in epithelium is related to the type of keratinization and/or its rate of cell turnover.