Sinus augmentation is a well-known approach to treating alveolar bone ridge atrophy in the posterior maxilla. The preparation of the lateral window is crucial. Its size, design, and position in the vestibular sinus wall may affect the intra- and postsurgical complication rates and affect the intrasurgical activity of both surgeons and assistants. The present paper describes a rational technique that also exploits the guided surgery approach for design and preparation of a lateral window for sinus augmentation, the Low Window Sinus Lift. To illustrate the use of this approach, a case is presented in which the 50-year-old patient had the left maxillary first molar extracted, followed two months later by sinus augmentation and placement of three implants. One year after delivery of the definitive prosthesis, all three implants were successful, and the prosthesis was fully functional. Controlled studies should be undertaken to assess whether this technique provides significant advantages compared to other sinus augmentation approaches.