External decompression is an effective treatment for acute intracranial hypertension, but the repair of cranial defect by cranioplasty is necessary sooner or later. Various materials have been used for cranioplasty, such as bone, metallic materials and methyl methacrylate. Alumina ceramic (Bioceram), which is known to be extremely compatible with tissues, has already been used in the operations of not only orthopedic and oral surgery but also neurosurgery such as transsphenoidal surgery and anterior cervical fusion. At first, we implanted pieces of ceramic and small titan shield in the parietal bone of mongrel dogs. In this experimental study, tissue compatibility and osteogenesis are investigated in each case. The new bone formation was observed macroscopically and histologically around the ceramic pieces, but there were no osteogenic changes around the titan shields. Then ceramic plates, which were designed just as patients' own bone flaps, and titan shields were used for cranioplasties after decompression surgery, and compared clinically and histologically. The ceramic plate is superior than the titan shield in its strength, tissue-compatibility and excellent fit for cranial defect compared with the titan shield. There was no tissue reaction such as subgaleal fluid collection just as seen in the application of acryl resin. We believe that Alumina ceramic (Bioceram) is a good material for cranioplasty.