Six block grafts harvested from the mandibular symphysis were used to augment partially atrophied ridges. Three maxillary defects and three mandibular defects were treated in five patients. Autologous bone grafts from the chin were stabilized in the recipient sites with resorbable pins and no membranes were used over the grafts. Healing proceeded without complciations. At 3 to 4 months the external cortical surface of the grafts progressively resorbed and the profiles of the pins protruded from underneath the buccal tissue that covered the a ugmented areas. However, the pins never perforated the tissue and they were resorbed macroscopically within 4 to 6 months. At 6 months the areas treated showed successful ridge augmentation and, when exposed for stage 2 surgery, remnants of the pin holes on the external surface of the repaired defects were detected. Radiographic evaluation of the block grafts was performed at 3 and 6 months and histologic specimens were obtained at 6 months; the specimens demonstrated incomplete pin resorption and encapsulation. A severe foreign-body reaction was detected in one case. The presence of an acellular bone matrix in certain sections and a normal bone pa ttern with a cellular component in others was a consistant finding. ITI endosseous implants were placed with excellent primary stability in all treated cases.