purpose: There are many procedures in Internal sinus floor elevation such as Osteotome technique, Localized management of sinus floor elevation, Antral membrane Balloon elevation, Hydraulic sinus condensation, On-site sinus condensation. It is neglected relation between width of maxillary sinus and choice of graft material, although medial wall of sinus membrane is almost not reflected in these procedure. The purpose of this study is to provide the modality of choice among graft materials though preoperative planning and measuring in CT images in Internal sinus floor elevation. Material & Method: In total of 40 patients, 70 implants were placed by lateral approached sinus floor elevation with autogenous bone graft. Postoperative CBCT scanning was performed and it was measured arrival distance of grafts from lateral wall to medial wall placed apex of implant in maxillary sinus. Result: Buccolingual arrival distances of grafts were measured as a mean 12.6mm±1.9 in postoperative CT images. In 44 cases(80%) among 55 cases of above 12.6mm, grafts were not contact to medial wall. In 12 cases (80%) among 15 cases of below 12.6mm, grafts were completely contact to medial wall. Conclusion: It should be measured buccolingual width of maxillary sinus which will be placed apex of implant in preoperative CT image. In below 12.6mm of width, graft materials with osteoinductive and osteoconductive potential are allowed to use in the Internal sinus floor elevation with bone graft, because osteoconductive effect from the medial wall is provided. In above 12.6mm of width, however autogenous bone with osteogenic potential should be used essentially.