Purpose: The possible advantages of stereolithographic (SLA) surgical template use have not been adequately demonstrated, and studies of the accuracy of computer-aided implant placement are few. The purpose of this in vivo study was to evaluate the accuracy of a computer-designed (SLA) surgical guide by comparing the three-dimensional positions of planned and placed implants. Materials and Methods: One hundred sixteen implants were inserted in partially and completely edentulous patients using multiple SLA templates. Preoperative and postoperative computed tomographic images were compared. Four deviation parameters-global, angular, depth, and lateral-were defined and calculated between the planned and actual implant positions and analyzed statistically. Results: The mean global deviations between planned and actual implant positions at the coronal and apical ends were 1.47 mm and 1.83 mm, respectively; the mean angular deviation was 5.09 degrees. There were significant linear correlations at the implant level between coronal and angular deviations and between coronal and apical deviations. Conclusions: The study highlighted deviations between the postoperative position and the preoperative plan at the coronal and apical portions of the implant, as well as in the angulation of the implant. Although the reported deviation values were extremely high, they do not appear to have resulted in important clinical complications. This suggests the necessity of always keeping a safety zone of at least 2 mm to avoid critical anatomical structures. Palabras clave: CAD/CAM surgical guide, computer-aided implantology, dental implants, stereolithography, surgical accuracy, surgical planning, surgical template