Summary The clinical and cytological effects of denture wear on the underlying palatal mucosa were studied in 67 complete denture patients. Forty-four persons without dentures served as the control group. Palatal keratinization under dentures was lower than the keratinization in the control group. Continuous denture wear, compared to daytime wear only did not reduce palatal keratinization. The appearance of leukocytes in smears from the palatal mucosa was related to the degree of mucosal keratinization but not to denture-wearing habits.