A retrospective study of 572 teeth treated with periapical surgery was undertaken in order to evaluate the influence of preoperative, operative and postoperative factors in the healing process as well as the operation method used. It was also the aim to assess whether the histophatological diagnosis of biopsies taken at the operation could be correlated to healing. Statistical analyses by the AID method and conventional cross-classification methods were performed. Factors of importance were found to be the extent of the destrucion, the operation method used, the bone surrounding the destruction, the quality of the orthograde root filling, the age of the patient, and the marginal bone buccally. The operation method was of importance in large destructions where root fillings were considered as not having properly sealed the canals, and when treating inflamed cysts. The histopathological diagnosis could not be ascribed any definite prognostic value.