Titania nanotubes and mesopores with different diameter sizes were prepared by electrochemical oxidation of titanium. The responses of osteoblastic cells isolated from Sprague-Dawley rats to the nanotube and mesopore layers were investigated in sequential events of cell adhesion, morphology, actin cytoskeleton, proliferation, differentiation, and mineralization. Nano-structural features, especially diameters of the nanotubes and mesopores, obviously influenced on cell behaviors in the sequential events. The cells showed better proliferation and differentiation abilities on the specimens with the nanotubes and mesopores than on flat titanium disk. Higher levers of calcium mineralization were observed on the nanotube and mesopore layers. The cells adhered much faster onto the nanotubes with about 170 nm diameter and the mesopores with about 400 nm diameter than onto flat titanium disk and 50 nm nanotubes. There is an appropriate range of the tube/pore sizes, and in this present work, titania nantubes with 170 nm diameter is the best for enhancing functions of osteoblasts.