Zirconium oxide ceramics have outstanding mechanical properties, a high biocompatibility and a high resistance to scratching. Expression profiling by DNA microarray is a molecular technology that allows the analysis of gene expression in a cell system. By using DNA microarrays containing 19,200 genes, we identified in osteoblast-like cells line (MG-63) cultured on zirconium oxide discs (Cercon, Degussa Dental, Hanau, Germany) several genes whose expression was significantly up or down-regulated. The differentially expressed genes cover a broad range of functional activities: (a) immunity, (b) vesicular transport and (c) cell cycle regulation. It was also possible to detect some genes whose function is unknown. The data reported are, to our knowledge, the first genetic portrait of a zirconium oxide surface. They can be relevant to better understand the molecular mechanism of biocompatibility and as a model for comparing other materials.