Exfoliative cytologic studies were carried out with 102 cases which had been enucleated, marsupialized or biopsied at the Department of Oral Surgery, Okayama University Medical School, and 15 cases of ameloblastoma were also studied as the disease which required differencial diagnosis. 1) The number of exfoliated cells showed a considerable difference between the cases. 2) The exfoliated cells from the cysts were appeared mostly as the individual cells and the aggregation of few cells, while the ceses of ameloblastoma showed a great number of cell aggregation in addition to them. 3) The cytoplasm: The stainability, the median palatine cyst, dermoid cysts and globulomaxillary cyst were well, postoperative buccal cysts, follicular dental cysts, radicular cysts and ameloblastomas were stained to an intermediate degree, while only the salivary retention cysts were stained poorly. As to the stainability according to colors most of the dermoid cyst cells were stained to yellow, but cells from other cases were stained in a blue color. Moreover dermoid cysts showed the superficial cells mostly, whereas in the other cases most of cells were from the intermediate layer. As for the contour shape, each cyst case presented a specific shape, polygonal, columnar and oval, which indicated the possibility of determination of the origin of epithelial cells to a certain degree. 4) Nucleus: While there could not be seen so much considerable differences in the nucleus as with the cytoplasm, there were some cases showing abnormalities such as irregularities in chromatin pattern, chromatin content, thickenning of the nuclear membrane, nuclear outline, multinucleation and anisokaryosis. 5) Nucleole: Some nucleoles showed abnormality in the number, stainability and contour but the degree of such abnormalities were less than cells from the malignant tumors. 6) The long diameters, short diameters and the area of cytoplasm showed significant differences in the cysts and ameloblastomas compared with normal buccal mucosa, while the same studies of the nuclei showed the significant differences could be founded some but not all of them. The C/N ratio were increased.