1. 1. Surgical mucoperiosteal flaps separating the gingiva from the teeth healed without any significant loss of periodontal attachment in all of the fifteen cases examined. 2. 2. Presence or absence of presurgical inflammation or variation in occlusal forces did not seem to influence the healing. 3. 3. By means of serial sectioning, it was possible to observe foreign bodies in the zones of previous surgery in six of the fifteen cases. Focal chronic inflammation was rather severe in three of these six cases three to four months after the flap procedure. 4. 4. Calculus should be removed routinely prior to flap operations, and suction should be used rather than sponges during the operation in order to avoid implantation of foreign bodies.