Purpose: The purpose of this study was to evaluate the outcome of the 3 different diameters of Brånemark System implants, with special focus on the 5.0-mm-diameter implant. Materials and Methods: Ninety-eight patients (99 jaws) with a mean age of 62 years were included in this retrospective report. The mean follow-up period was 2 years and 8 months. A total of 379 Brånemark System implants (3.75 mm diameter, n = 146; 4.0 mm diameter, n = 76; 5.0 mm diameter, n = 157) were placed in 29 edentulous and 70 partially edentulous jaws. Results: Eight of the 146 implants in the 3.75-mm-diameter group failed (5.5%). The corresponding figures for the 4.0- and 5.0-mm-diameter implants were 3 of 76 (3.9%) and 7 of 157 (4.5%), respectively. Discussion: All failures were recorded in maxillae, ie, 18 of the 298 placed, and the majority of these were found in bone quantity group B and quality group 2. Only 3 implants of 131 failed in bone judged as quality 4. The marginal bone loss was low for the 3 implant diameter groups. Conclusion: The favorable outcome in bone of poor quality is ascribed partly to the use of an adapted preparation technique and extended healing periods for achievement of the best primary and secondary implant stability possible.