Following tooth extraction, a socket often presents dimensions that may be considerably greater that the diameter of a conventional implant. The present experiment was performed to study the healing that occurred adjacent to implants placed in recipient sites with a wide marginal defect. Four Labrador dogs were used. In the right side of the mandible, four experimental sites were prepared to receive titanium implants [sandblasted, large-grit, acid-etched (SLA) surface]. Traditional implant installation (control) was performed in one site. In the remaining three sites (test), a step drill was used to widen the marginal 5 mm of the canal. Following placement of an implant in a test site, a circumferential gap about 1-1.25 mm wide and 5 mm deep was present lateral to the implant. A resorbable barrier membrane was used to cover the implant and the bone tissue of two sites, while one site was left uncovered. Four months following implant installation, block biopsies of each implant site were obtained and prepared for ground sectioning. After 4 months of healing, the large marginal defect had been filled with newly formed bone. The degree of bone-to-implant contact between the newly formed tissue and the SLA surface was at all test sites high and similar to that obtained at control sites. The placement of a barrier membrane following implant installation did not improve the outcome of healing. We conclude that a marginal defect wider than 1 mm may heal with new bone and a high degree of osseointegration to an implant designed with a SLA surface.