Introduction: Maxillary posterior region, compared to the mandible or maxillary anterior region, has a thin cortical bone layer and is largel y composed of cancellous bone, and therefore, it is often difficult to achieve primary stability. In such cases, sinus elevation wit h bone graft is necessary. Materials and Methods: In this research, 121 patients who had implant placement after bone graft were subjected to a follow-up study of 5 years from the moment of the initial surgery. The total survival rate, 5-year cumulative survival rate and the influence of the follo wing factors on implant survival were evaluated; the condition of the patient (sex, age, general body condition), the site of implant placement, diamet er and length of the implant, sinus elevation technique, closure method for osseous window, type of prosthesis and opposing teeth. Results: 1. The 5-year cumulative survival rate of total implants was 90.5%, there was no significant difference between sex, age, the s ite of implant placement, diameter and length of the implant, sinus elevation technique, and the type of opposing teeth. 2. Patients with diabetes mellitus & osteoporosis and smooth-surfaced machined group & hydroxyapatite (HA)-treated group and ho mogenous demineralized freeze dried allogenic bone (DFDB) bone graft only group had significantly lower survival rate. 3. With less than 4 mm of residual alveolar ridge height, lateral approach without closing the osseous window resulted in a sig nificantly lower survival rate. 4. Restoration of a single implant showed a significantly lower survival rate, compared to cases where the superstructure was j oined with several implants in the area. Conclusion: Patients with diabetes or osteoporosis need longer period of time for osseointegration compared to the normal, and the dentists must be prudent when choosing a surface treatment type and the bone graft material. Also, as the vertical dimension of the residual alv eolar ridge can influence the result, staged implant placement should be considered when it seems difficult for the implant to gain primary stability fro m the residual bone with less than 4 mm of vertical dimension. It is recommended to obdurate the bone window and that the superstructure be connected wi th several impants in the peripheral area.