Background: Sinus elevation is a reliable and often used technique. The success of implants placed in such situations, even with bone substitutes alone, led us to strive for bone loss close to zero and to seek out variables that cause higher or lower rates of resorption. The objective of this study was twofold: to evaluate the survival rates and marginal bone loss (MBL) around implants installed in maxillary sinus augmentation using anorganic bovine bone, and to identify surgical and prosthetic prognostic variables. Methods: A total of 55 implants were placed in 30 grafted maxillary sinuses in 24 patients. Periapical radiographs were evaluated immediately after implant placement (at baseline), at 6 months, and at the most recent follow-up. MBL was calculated, taking into account the distortion rate for each radiograph as compared to the original implant measurements, from the difference between the initial and final measurements. Results: The survival rate was 98.2%, with only one implant lost (100% survival rate after loading) over a mean follow-up time of 2 ± 0.9 years. The MBL ranged from 0 to 2.85 mm: 75.9% of mesial sites and 83.4% of distal sites showed <1mm of MBL, while 35.2% of mesial sites and 37% of distal sites exhibited no bone loss. The MBL was significantly (p<0.05) greater in open flap as compared to flapless surgery. Conclusion: Within the limitations of this study, we concluded that maxillary sinus elevation with 100% anorganic bovine bone presents predictable results, and that flapless surgery results in less MBL as compared to traditional open flap surgery.