Purpose: The aim of this study was to compare the complication rates of recipient sites prepared using two incision techniques: crestal and tunnel. Materials and Methods: In this prospective study, patients underwent augmentation procedures (68 patients; 75 sites) by the same surgeon that were performed consecutively using the crestal incision technique (27 horizontal, 10 vertical; crestal group) or the tunnel incision technique (27 horizontal, 11 vertical; tunnel group). Autogenous bone block grafts were harvested with a piezoelectric surgical device, and the grafts were fixed at the recipient sites by two titanium screws in both groups. The authors evaluated minor exposure, transient paresthesia, major exposure, permanent paresthesia, gingival recession at adjacent teeth, surgery time, and visual analog scale pain scores. Results: Soft tissue dehiscence and graft failure were significantly lower in patients undergoing the tunnel technique. Conclusion: The tunnel incision technique significantly decreased soft tissue exposure, the most common complication of augmentation procedures with autogenous onlay bone grafts. This technique should be considered an alternative to the crestal incision technique for preparation of the recipient site. Keywords: alveolar ridge augmentation, autogenous bone, complication, failure, minimally invasive surgery, subperiosteal tunnel technique