Maxillary sinus floor elevation is an effective method for bone augmentation in the posterior maxilla. Due to the limitations of autogenous bone grafts, bone substitutes are often used for this purpose. This study sought to compare the histologic and histomorphometric results of using NanoBone® and easy-graft™CRYSTAL for maxillary sinus floor elevation. This randomized double-blind split-mouth clinical trial was conducted on nine healthy patients requiring bilateral (n=18) sinus floor augmentation. Dental implants were placed six months after sinus floor elevation. Biopsy samples were taken at the time of implant surgery and analyzed using HistoMorphoMeter Ver.1.0 software. Histomorphometric analysis indicated that NanoBone® and easy-graft™ residues accounted for 32.71±10.39% and 26.61±9.48% of the bioptical volume, respectively. The amount of new bone formation was 25.29±7.29% and 18.69±5.63% in the NanoBone® and easy-graft™ groups, respectively. Paired samples t-test showed significant differences between the two groups in this respect (P=0.0001). Wellmineralized regenerated bone with lamellar parallel-fibered structure and Haversian systems surrounded the particles in both groups. Both tested materials yielded acceptable histological outcomes six months after surgery. NanoBone® caused superior new bone formation. Although longer follow-ups and larger sample size are needed, these preliminary results encourage further research in this respect