Conventional orthopedic implants are composed from titanium. To improve some characteristics (ie, volumetric porosity, modulus of elasticity, frictional modulus), a new porous tantalum biomaterial has been developed and its biocompatibility reported. By using DNA microarrays containing 20,000 genes, several genes whose expression were significantly up- or down-regulated were identified in an osteoblastlike cell line (MG63) cultured with tantalum powder (TP). The differentially expressed genes cover a broad range of functional activities: signaling transduction; transcription; cell cycle regulation, proliferation, and apoptosis; and cytoskeleton formation. To the authors' knowledge, the data reported represent the first genetic portrait of TP.