Objective: This study aims to evaluate the relationship between implant placement, poor quality bone, simvastatin, and osseo-integration of surface-treated implants in the posterior maxilla of osteoporotic rats. Materials and methods: Sixty-four female Sprague-Dawley rats, aged 3 months old were used in this study, divided into three groups: Sham-operated (SHAM; n = 20), ovariectomized (OVX; n = 20) and ovariectomized treated with simvastatin (OVX + SIM; n = 20). Two rats from the SHAM and two from the OVX groups were used to verify osteoporosis. Eighty-four days following ovariectomy, screw-shaped titanium implants were immediately placed into mesial root sockets of the posterior maxilla. Simvastatin was administered orally at 5 mg/kg each day after the implant placement in the OVX + SIM group. The animals were sacrificed at either 28 or 56 days from the date of implant insert and the undecalcified tissue sections were processed for histological analysis. The osseo-integration indices used were: bone formation rate (BFR), bone to implant contact (BIC), and bone density (BD). Results: The osseo-integration indices (BFR, BIC and BD) in the three groups demonstrated significant differences among the SHAM > OVX + SIM > OVX group, which implied that simvastatin could promote bone mineralization in OVX rats. Conclusion: This study shows for the first time that simvastatin can positively affect the osseo-integration indices, and successfully promoted osseo-integration in the posterior maxilla in OP rats.