Minimally invasive microsurgery performed using an operating microscope (OM) has shown accelerated and improved wound healing for periodontal plastic and regenerative procedures. This case series aims to demonstrate the potential usefulness of OM for maxillary sinus augmentation in a private practice setting. Twelve vertical sinus augmentations (VSAs) and 8 lateral sinus augmentations (LSAs) were performed with the assistance of OM. Flap reflection, osteotomy, sinus membrane elevation, membrane integrity evaluation, implant placement (if indicated), and wound approximation with sutures were performed under OM. After a minimum healing period of 6 months, radiographic bone height gain was assessed. One sinus membrane perforation was observed during VSA surgery. The mean vertical bone gain was 4.82 ± 1.31 mm and 8.36 ± 1.45 mm for VSA and LSA, respectively, with 100% implant success rate. OM-assisted maxillary sinus augmentation provides favorable clinical visualization, thus facilitating delicate hard and soft tissue manipulation.