This paper reports histologic and histomorphometric results concerning bone healing around 13 pure titanium screw-shaped root-form implants that were placed in three mongrel dogs immediately after extraction of maxillary and mandibular premolars. Osseous healing around the implants showed a great deal of variability depending on the arch in which the implant was placed and on the original anatomy of the implant site. Implants placed in the mandible showed the greatest amount of bone apposition, with a mean total bone of 60.3%. Implants placed in the maxilla showed less bone and greater variability both visually and statistically, with a mean total bone of 46.3%. The values obtained for bone after 5 months of healing of the control sites were consistent with the values obtained for bone approximating the implants after the same time period. This was true for both arches. It was impossible to visually or statistically discriminate between sham surgical control sites and routine control sites or between implant sites and either of the control sites. Implant surgical procedures and implant placement seemed to have little effect on the tabulated values beyond tooth extraction alone. This research suggests that immediate implants have the potential for developing good bone apposition depending on the area of implantation. Schlagwörter: animal, bone, dog, endosseous implant, extraction, healing, histology, histomorphometry, morphometry