Purpose: The purpose of this study was to assess the reliability of the planning software of an imageguided implant placement system based on a mechanical device coupled with a template stabilized on soft tissue during surgery. Materials and Methods: Thirty consecutive partially or completely edentulous patients were treated with the image-guided system. For each patient, a study prosthesis was fabricated and duplicated in acrylic resin and served as a scanning template. Axial images were obtained from a computerized tomographic scan and transferred to planning software that provides real 3- dimensional information to plan implant position. Once the final position of the implant was defined, preoperative data such as the size of implants and anatomic complications were recorded using the planning software. The scanning template was then drilled in that exact position by a drilling machine. During surgery, the drilled template was used as a drill guide. After implant placement, intraoperative data were recorded and statistically compared with the preoperative data using the Kendall correlation coefficient for qualitative data and the Kappa concordance coefficient for quantitative data. Results: Agreement between the preoperative and intraoperative data was high for both implant size and anatomic complications. The Kendall correlation coefficient was 0.8 for the diameter and 0.82 for the length. The Kappa concordance coefficient was 0.87 for both dehiscence and bone graft, 0.88 for osteotomy, and 1.0 for fenestration. Discussion: In the few instances where planning was not perfect, implant placement was completed in a clinically acceptable manner. Conclusion: The results suggest that the image-guided system presented is reliable for the preoperative assessment of implant size and anatomic complications. It may also be reliable for flapless surgery.