The healing processes of deciduous tooth socket after extraction seems to have some influence on the growth of permanent teeth. As for the studies on healing processes of extraction wound of teeth, there are many reports by Euler (1932), Hahn (1958), Smith (1958), and Tomozawa (1973), but as far as we know, there is no report dealing with deciduous teeth. For this reason, using pups (about 3 months old, weighing 1.5Kg-3.0Kg, about the same solidification of eruption of deciduous teeth and calcification of permanent teeth germ) the first and second frontal teeth of upper jaw of the right and left sides, and the first and third frontal teeth on the right and left sides were extracted. Then exfoliative cytological, pathohistological as well as macroscopic observations were carried out on the healing processes of the extraction wound with lapse of time, and the following results were obtained. It was found that 15 days after tooth extraction the maturity of epithelial cells became quite marked, and by 30 postoperative days exfoliated cells gave the findings similar to those of normal gingiva. The proliferation of the subepithelial connective tissue was marked by 5-10 postoperative days. After 20 days and later the exfoliative cytological findings revealed an acute increase in the number of precornified cells, and the pathohistological findings showed a tendency of parakeratosis. Macroscopic findings indicated a decrease in erythema, swelling and exudative substances, and the shrinkage of scar could be recognized by 15 days and thereafter.