Purpose: This study aimed to evaluate (1) the association between implant diameter and marginal bone loss (MBL) of short (6 mm) implants and (2) the survival rates of short implants. Materials and Methods: Thirty-three 6-mm implants were placed in the mandibles of 16 qualified patients. The selected sites had > 5 mm ridge width and 9 mm bone height. None of the implant sites required bone augmentation procedures. All implants were uncovered 3 months after placement, and all patients were rehabilitated with 2- or 3-unit implant-supported fixed partial dentures. Standardized periapical films were taken after 24 months of function. Radiographs were digitalized, and MBL was assessed. Results: For all implants, the mean MBL was 0.17 mm at the point of uncovering. At the 2-year follow-up, all implants were immobile and functional. Implants with 4.2-mm diameters had significantly more MBL (1.95 mm) than wider implants (0.47 mm and 0.35 mm for 5.0-mm and 6.0-mm implants, respectively). Conclusion: This 2-year study illustrated that short implants are a viable option in selected clinical scenarios. Short implants with wider diameters are preferred because they have less marginal implant bone loss. Keywords: alveolar bone loss, dental implants, dental restorations failure, mandible