Porous ceramic (Al2O3) implants with a pore size of 100--750 mum were used in the surgical treatment of four patients at the Department of Oral Surgery and Oral Medicine, Dental Faculty, University of Oslo. In two of the cases, ceramic implants were placed in small surgical defects in the edentulous maxillary alveolar ridge, while two patients were treated with mandibular ridge augmentation. All four individuals healed uneventfully, and the implants were firm and immovable 3 weeks postoperatively. No adverse tissue reactions were observed. Dentures were inserted over the implants 8 days to 6 weeks after implantation. In one of the cases, reoperation was performed because of 2 X 2 mm zone of exposure of the ceramic 4 weeks after denture insertion. Examination after observation times up to 15 months revealed clinically normal soft tissue over the implants. There were no complaints about wearing of the dentures. Radiographs at varying intervals after implantation did not disclose any pathologic changes or signs of resorption of bone adjacent to the ceramic implants.