There have been many expanded applications for the use of endosseous implants in the reconstruction of partially and totally edentulous patients. The posterior maxilla, which frequently has inadequate quality and quantity of bone, and the contiguous maxillary sinus often provide poor recipient sites for endosseous implants. However, innovative procedures using autogenous, allogeneic, and alloplastic graft materials have enabled clinicians to place implants in the reconstructed resorbed maxilla. These techniques often violate the anatomic integrity and interfere with the physiologic mechanisms of the maxillary sinus, creating potential complications. Eight patients with complications following maxillary sinus augmentation and reconstruction with endosseous implants are reported. Keywords: bone graft, complications, implant, infection, maxillary sinus