Purpose: The purpose of this study was to evaluate the results of the repair of perforated sinus membranes with resorbable collagen membrane. Materials and Methods: A split-mouth design was followed. Twelve subjects requiring bilateral sinus grafting were included in the study; one site had been accidentally perforated during sinus augmentation and the other site had not been perforated. The perforated sites were repaired with a resorbable collagen membrane. Dental implants were placed during a second surgery, and biopsy samples were harvested from both sinuses during implant placement. New bone formation was measured for all sites. Implant survival was recorded at second-stage surgery. Panoramic radiographs were taken before and after sinus grafting and after implant placement. Results: Nonperforated sites demonstrated significantly more bone formation (33.58% ± 7.45%) than perforated sites (14.17% ± 7.06%) (P .0001). Perforated sites demonstrated significantly more soft tissue formation (63.58% ± 12.96%) than nonperforated sites (48.5% ± 12.57%) (P = .006). In nonperforated sites, residual graft particles had more of their surface in contact with bone (40.17% ± 14.92%) than perforated sites (14.5% ± 12.03%) (P .0001). The implant survival rate at secondstage surgery was superior for nonperforated sites (100%) in comparison to perforated sites (69.56%) (P = .0028). Discussion: This study suggested that repairing the perforated site of the sinus membrane with a resorbable collagen membrane may result in reduced bone formation and implant survival rate. A different technique and/or materials than those used in the current study may offer better results for the repair of the perforated sinus membrane. Conclusion: The study demonstrated that perforation and repair of the sinus membrane may compromise new bone formation and implant survival.