Objective:To evaluate clinical effect of deproteinized bovine bone for delayed implantation after fenestration.Methods:This trial is a continuation of a prospective clinical trial. From May 2011 to February 2015 in Department of Implantology, School of Stomatology, The Fourth Military Medical University after planting division of 55 cases of maxillary teeth missing area of residual alveolar bone height ≤5 mm patients. There were 21 female and 34 male patients, their average age were (55.2±7.1) years. A total of 62 side fenestration of maxillary sinus floor lift, clinical and imaging examination, evaluation of implant retention rate, complications, peripheral soft tissue health and marginal bone resorption.Results:A total of 82 implants were followed up in 41 patients. The average follow-up time was (51.8±14.3) months (36-78 months). The follow-up rate of the maxillary sinus was 75.8% (47/62), the follow-up rate of the implant was 73.9% (82/111), and the implant survival rate was 98.8% (81/82). The bone resorption results at the implant margins were (0.64±0.63) mm (-0.28 mm, 1.47 mm) in the near and (0.49±0.73) mm (-0.51 mm, 1.21 mm) in the far, the improved hemorrhage index was 0.46±0.72, the improved plaque index was 0.60±0.87, and the keratinized mucosa width was (2.14±1.22) mm. The incidence rate of peri-implant mucositis was 28.4% (23/81) among 23 implants, and there was no complication of peri-implant inflammation.Conclusions:This study shows that under the condition of insufficient sinus ridge spacing in the maxillary posterior area, it is feasible to use bovine bone alone to remove protein for delayed implantation of maxillary sinus floor elevation by windowing, and the clinical effect is reliable.