Purpose: The aims of this study were to evaluate the incidence of maxillary sinusitis associated with the sinus elevation procedure and to analyze the influence of maxillary sinusitis on the prognosis of dental implants. Materials and Methods: Data were collected from medical records and dental radiographic findings of patients who received dental implant therapy along with a sinus elevation procedure at Seoul National University Bundang Hospital from June 2003 to December 2008. Results: A total of 338 sinus elevation cases (643 implants) were included in this study, out of which maxillary sinusitis was reported in 33 cases (9.8%). The type of surgical approach used and the occurrence of sinus membrane perforation could be considered factors affecting maxillary sinusitis associated with the sinus elevation procedure. The implants at the site of the maxillary sinusitis associated with the sinus elevation procedure showed lower survival rates in male patients. Better clinical outcomes were achieved in the group receiving combined medical and surgical therapy for sinusitis associated with the sinus elevation procedure. Conclusions: Postoperative maxillary sinusitis decreased the survival rates of implants, whereas early diagnosis and combined medical and surgical therapy had the opposite effect. Keywords: maxillary sinusitis, sinus elevation, dental implants, prognosis