The clinical success of dental implants is governed in part by surface properties of implants and their interactions with the surrounding tissues. The objective of this study was to investigate the effect of heat-treated titanium (Ti) surfaces on protein adsorption and osteoblast responsesin vitro. The passivated Ti samples used in this study were either nonheat-treated or heat-treated at 750°C for 90 minutes. Using x-ray diffraction analyses, no oxide peaks were observed on the nonheat-treated surfaces, suggesting an amorphous oxide. Crystalline rutile TiO2peaks were observed on the heat-treated Ti surfaces. The contact angles of water on heat-treated Ti surfaces (32.0 ± 2.5 degrees) were statisti cally lower compared with the nonheat-treated Ti surfaces (47.7 ± 2.3 degrees). In addition, the mean albumin concentration on the nonheat-treated Ti surfaces (3.57 ± 0.33 μg/mL) was observed to be significantly different from the mean albumin concentration on heat-treated Ti surfaces (2.25 ± 0.26 μg/mL). In the presence of an osteoblast precursor cell line, significantly different hexosaminidase activity, protein production, and alkaline phosphatase activity were observed for cells grown on heattreated Ti surfaces compared with nonheat-treated Ti surfaces.