A large variety of bioceramics have been successfully utilized as implant materials for promoting fixation of bony tissues. Different bioceramics exhibited markedly different proliferation rates of the osteoblast cells in vitro. Clarification of the mechanism about the attachment and proliferation/differentiation of the cells would contribute to selecting suitable biomaterials for hard tissue replacement. Nanostructured hydroxyapatite (HA) coatings have been produced and they have shown promising mechanical performances. The present study employed the 2-dimentional gel electrophoresis assay for comprehensively studying the proteomics of the cells proliferated on the nanostructured HA coating. Mass spectrometry analysis was conducted to characterize the specific proteins. Results showed that the nanostructured HA coatings enhanced proliferation of the osteoblast cells. Alkaline phosphatase (ALP) assay revealed an increased ALP activity of the nanostructured coating, and obviously the presence of the nanosized pores can promote the anchoring and stretching of the cells. No obvious difference in the 2-D gel maps taken for the cells proliferated on the HA coating and for control can be found. This in turn suggests that the nanostructured HA coating induces no changes in the cells. The promoted cell proliferation by the HA coating could then be possibly explained by the affected apoptosis of the cells.