Purpose: To evaluate a novel surgical technique for flapless transcrestal elevation of the maxillary sinus floor via surgical templates using gel pressure. Materials and Methods: Computed tomographic scans of fresh human cadaver maxillae and three-dimensional treatment planning software were used to design surgical templates. Access to the maxillary sinus was gained by guided transcrestal osteotomies to puncture the bony sinus floor. By injection of radiopaque gel, the maxillary sinus membrane was elevated to attain a postoperative bone height of 15 mm. Results: The gel-pressure technique was performed in 10 atrophic maxillary sites with a mean residual bone height of the alveolar crest of 4.7 ± 1.6 mm. The sinus membrane was successfully elevated in all sites without causing iatrogenic perforation (mean elevation height, 10.6 ± 1.6 mm). Conclusions: The gel-pressure technique may provide a new option for minimally invasive transcrestal sinus surgery and may represent a safe method to increase bone volume in the atrophic posterior maxilla. Keywords: bone augmentation, dental implants, maxillary sinus, minimally invasive surgery, surgical templates