Purpose: The purpose of this study was to provide feasibility of a new technique of sinus graft: outfracture osteotomy sinus graft. Materials and Methods: The author modified the window opening method from the original trapdoor technique to an outfracturing and readaptation technique. It provides a few advantages in dental implant treatment of atrophic maxillary posterior edentulous alveolar ridges: 1) in combined cases of height and width problems; 2) in cases with anatomic problems such as sinus septum, thick lateral sinus wall, and intrabony bleedings; 3) possible use of the outfractured bony segment as a covering membrane. Results: The follow-up of 34 patients (40 cases; 6 bilateral cases) revealed good results without a case of graft failure and showed excellent survival and function of the dental implants. Conclusion: The sinus graft technique was modified as the author outfractured and readapted the bony lateral window, with several advantages as mentioned above. This new outfracture osteotomy sinus graft technique has excellent results as an alternative to the original trapdoor technique.