The effect of surface roughness of ground Ti on the initial adhesion of osteoblast-like U-2 OS cells was investigated in this study. Different numbers (#120, #600, and #1500) of SiC sandpaper and two Al2O3 polishing powder (0.3 and 1 microm) were used to prepare the metal specimens with varying degrees of surface roughness. Surface roughness (Ra) was measured by profilometry. Surface topography was observed using an atomic force microscope. MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide) assay was used to measure the optical density (OD) of specimens after 2 h of cell incubation. The OD value was analyzed by one-way ANOVA for analyzing the factor of surface roughness. Crystal violet staining technique was used to characterize the cell spreading. Results showed that the specimen of #1500 Ti (Ra: 0.15 microm) had the highest OD value. The specimens polished with 0.3 and 1 microm Al2O3 powder (Ra: 0.05 and 0.07 microm) exhibited the worst cell adhesion behavior. Contact guidance of cells could be observed on the rougher #600 and #120 specimens (Ra: 0.33 and 1.20 microm). This study concludes that the surface roughness (Ra: 0.05-1.20 microm) of ground Ti has a highly significant influence on the initial adhesion of osteoblast-like U-2 OS cells. The ground Ti with an Ra of 0.15 microm shows the optimal cell adhesion behavior with respect to either the rougher or smoother specimens.