Initial pilot studies using tricalcium phosphate ceramic placed into human periodontal osseous defects demonstrated osseous repair. Therefore, further evaluation of this material was undertaken on 17 carefully selected patients with 1-wall, 2-wall, crestal and furcation defects using standardized preoperative and postoperative radiographs, clinical measurements and clinical photographs. Inverse bevel, full-thickness flaps were raised, the areas debrided, root surfaces planed with ultrasonic and hand instrumentation, osseous penetrations made with curet point and the flaps sutured after the defects were filled. Eighteen-month reentry surgical procedures were performed on 10 of the 17 patients, with a resultant average of 2.8 mm of new bone. Controls were not used in this study since a protocol describing a sham procedure with other than 3-wall osseous defects was not acceptable in 1973 to the Clinical Human Use Committee. Although the tricalcium phosphate ceramic material was not found to be totally predictable in this study, it may nevertheless become a useful graft material because of its potential for osseous repair in combination with its availability, host acceptability, ease of manipulation and storage advantages.