The purpose of this article is to compare the larger (8 × 10-mm single implant and 15 × 20-mm multiple implant) lateral window designs used in the sinus elevation procedure with a newly proposed, less-invasive window design and discuss the advantages and limitations of the new design. The less-invasive window designs differ from the larger window designs in both the size and shape of lateral windows. Following creation of a round-window osteotomy, the quality of the sinus membrane and its ability to be elevated are assessed. The initial window can then be enlarged as a vertical oval window for a single implant or a horizontal oval window for multiple implants. The advantages of these window designs include the preservation of the lateral walls, blood supply to bone grafts, and better containment of the graft material. The limitations of these window designs are decreased visibility, accessibility for correcting a membrane perforation, and access for draining a sinus infection if one occurs. These complications necessitate increasing the size of the window as needed for successful treatment. The proposed less-invasive window design provides distinct advantages for a successful sinus elevation procedure and decreased patient morbidity.