Keratocysts may develop from cellular multiplication, from recidivating growth of epithelial cells left after curettage, and they have an important potential growth, they can degenerate into malignancies. There are several etiological possibilities: tissues connected with crown formation, invagination of nucous epithelium, degeneration of follicular cysts producing keratin. The most important characteristic of these cysts is the frequent recidivation. Fron a clinical standpoint, they are classified as benign tumors. After enucleation, the walls of healthy tissue should be reduced, particularly in locations where the access of curettes is difficult. If necessary, apicetomy is performed in order to completely eliminate the cyst walls. Histological examination is mandatory. Finally, radiologic controls during at least six years should be made.