Periodontal surgery (open) is defined as intentional severing or incising of gingival tissue with the purpose of controlling or eliminating periodontal disease. Therefore, scaling and root planing (blind or closed) are not included. A periodontal flap is a section of gingiva and/or mucosa, surgically elevated from the underlying tissues to provide visibility and access to the bone and root surface. This chapter covers the indications/objectives of flap surgery, incisions, papilla preservation flap, flap techniques for pocket therapy, distal molar surgery, healing after flap surgery, and healing after full thickness flap. Periodontal flap is classified as according to the thickness of the flap/bone exposure after flap reflection, according to the placement of flap after surgery, and according to design of the flap/management of the papilla.