For histologic observation of the regenerated bone following guided tissue regeneration (GTR) using ePTFE membranes with calcium carbonate implant and autogenous bone graft, biopsies were collected from 2 patients during 5-year-postoperative surgical reentry. In both combined cases with guided tissue regeneration in conjunction with calcium carbonate implant and autogenous bone graft, significant bone fill and gain in probing attachment level was observed. In histologic examination, specimen in GTR case with calcium carbonate grafting was composed of a dense bone containing vascular channel with lamellar structure and viable bone cells in lacunae, however considerable calcium carbonate particles remained unresorbed and isolated from regenerated bone by the dense cellular and fibrous connective tissue. No formative cells could be seen in contact with remained calcium carbonate particles. In GTR case with autogenous bone grafting, specimen show was composed of a dense lamellar bone containing vascular channel, which showed normal alveolar bone architectures. The present observation indicate that guided tissue regeneration in conjunction with grafting, especially autogenous bone graft, has highly osteogenic potential, however resorbable calcium carbonate granules were not completely resorbed at 5 year postimplantation.