Sixty five normal mature dogs weighing about 5 to 10Kg. fed on under the same condition were used. Gingivectomies were performed in the area of lower anterior teeth, while flap operation in the area of upper anterior teeth in the same dog. Healing process of operated gingivae was followed up during twenty-eight days after operative procedure. Imagawa's gutta percha perfusion methode was adopted for observation immdeiately after, 1day, 3, 7, 14, 21 and 28 days after operation consecutively, and then heads of sacrificed dogs were fixed in 10 percent formalin solution. Transparent specimens were prepared from the operated tissue for stereoscopic observation, while histologic specimens were stained with hematoxylin-eosin by a routine paraffin methode simultaneously. The result obtained were as followed: 1) Vascularization during wound healing of the operated gingiva, alveolar bone and periodontal membrane was fundamentally identical with description by Clark and Akita: new capillary loops which developed from capillary buds connected each other and built a capillary net work on the seventh days and then some capillaries disintegrated. 2) Clusters of capillary loops which developed in the granulation tissue were mainly supplied by the blood vessels of the periodontal membrane especially in the case of gingivectomy. Thus it could be considered that blood vessels of periodontal membrane would play the most important role in the blood supply for the newly formed gingiva in the early stage. 3) Newly formed blood vessles of the gingiva and periodontal membrane as well as branch vessels among of capillary loops were connected each other fourteen days after operation, 4) Reattachment of gingiva to cemeutum was noticed two weeks after operation. At this period capillary loops, which had developed in the wound of flap operations, built capillary net works at the area internal gingival epithelial margin (innere Saumepithel) and were shortened and came closer to cementum at the area where internal gingival epithelial margin attached. It would be considered that this process would stimulate the vitality of cementum and had some relationship in organic union of the connective tissue with cementum. 5) Wound healing was remarkably delayed at gingival papillae, where normal vascularization could not be noticed 28days after operation. Thus it would be better for us to use surgical packs after operation and gingival massage seemed to stimulate normal vascularization.