Objective: The objective of this study was to histologically and histomorphometrically evaluate the efficacy of the new formulations of eggshell-derived calcium carbonate in rats. Study Design: The study was conducted on 30 adult male rats. Four standardized and circular intra-bony defects were created in the both maxilla and mandibula of each animal. Three different graft materials were prepared as follows: 1) Material A: Eggshell-derived calcium carbonate combined with carrageenan gel, 2) Material B: Eggshellderived calcium carbonate combined with xanthan gum gel, and 3) Material C: Eggshell-derived calcium carbonate powder. The right mandibular defect sites were grafted with Material A in all animals, and defects on the left were grafted with Material B. Defects on the right side of maxilla were received Material C in all animals, and all left maxillary defects were remained untreated as controls. The animals were sacrificed either postoperatively on the 15th day, postoperatively on the 30th day or postoperatively on the 45th day. Histomorphometric measurements were made of the areas of newly formed bone, necrotic bone, fibrous tissue and residual graft material. Results: Material A exhibited the highest level of osteoid formation followed by Material B and Material C on the 45th day. In terms of osteoid formation, statistically significant differences were observed between graft materials and controls at 45th day compared to 15th and 30th day (p<0.05). Conclusions: Eggshell-derived graft substitutes in both gel and powder forms are biocompatible materials which may have the potential to enhance the new bone formation.