The bone-bonding ability of a glass ceramic can be evaluated by using simulated body fluid (SBF). Furthermore, rat primary osteoblast cell culture is effective in collecting preliminary information for potential application of any material of organic or inorganic origin. In this study, the effect or CeO2 addition on crystallization behavior and bioactivity of potassium mica and fluorapatite based glass ceramics was investigated. Also an osteoblast cell culture model was utilized to investigate the effect of CeO2 addition on biocompatibility of potassium mica and fluorapatite based glass ceramics by using biological criteria such as cell viability, metabolic activity and nitric oxide production. (C) 2009 The Ceramic Society of Japan. All rights reserved.