It is challenging for many clinicians to install dental implant on atrophic and pneumatized alveolar bone. There are many anatomical barriers, such as limited visual field, easy-torn Schneiderian membrane, short and narrow alveolar bone and posterior superior alveolar arteries and veins. Furthermore, many prosthodontic considerations are needed for rehabilitation of posterior maxilla, such as crossbite and short occlusal height. The purpose of this study is to report success of simultaneous dental implant installation with maxillary sinus floor augmentation on severely resorbed alveolar bone. From the results of the cases, combined procedures of installation of implant and maxillary sinus floor augmentation at the same time may be a predictable procedure if it is conducted by an experienced expert.