Aim. The objective of the present study was to elucidate the dynamics of morphological changes in the epithelial tissue of the patients suffering from intolerance of the materials of the removable dentures and those wearing nylon partial dentures. Material and methods. We have undertaken a comparative clinical and laboratory study with the purpose of evaluation of the morphological structure of the oral mucosa in the patients presenting with intolerance of the denture materials and nylon prostheses. The control group was comprised of the patients with satisfactory results of the treatment while the representative group consisted of the patients with complaints arising in connection with the appication of the prostheses after their placement and fixation. Smear-scrapings were taken not earlier than 2 hours after a meal without the preliminary rinsing of the oral cavity. The scrapings were prepared using a standard Folkman spoon by slightly pressuring it to the inner surface of the cheek where the bottom crease passes into the bottom of the oral cavity. The specimens thus obtained were stained with hematoxylin and eosin and examined under a light microscope. Results. The dynamics of the state of mucosal epithelium in the patients using the nylon dentures and satisfied with the quality of prosthetics, when compared with the similar findings in the patients with acrylic dentures was characterized by the significantly less pronounced variations in the number of intermediate cells, which almost completely altered back to the pre-prosthetics level during the period of adaptation. It was demonstrated that the dentures made from thermoplastics produced a much less pronounced detrimental effect on the oral soft tissues. The evaluation of the influence of the nylon partial dentures on the epithelium of the patients presenting with the symptoms of intolerance revealed the tendency toward the steady decline in the amount of the surface cells. Moreover, this tendency was apparent from the beginning of the study (within the first 7 days) and remained unaltered during the following 60 days. In addition, the number of the parabasal cells increased. Conclusion. The morphological changes in the oral mucous epithelium of the patients wearing nylon dentures are insignificant in comparison with the changes associated with the application of the removable acrylic dentures.