Titanium oxide nanotubes prepared by anodization have received considerable attention in the biomaterials domain. The objective of this study was to demonstrate the electrochemical behavior of different diameter TiO 2 nanotube layers on titanium in phosphate buffered saline (PBS) and Dulbecco's minimum essential medium+10% fetal calf serum (D-FCS) using open circuit potentials (OCP), electrical impedance spectroscopy (EIS), and a potentiodynamic polarization test. The results showed that the nanotubes had higher OCP, higher resistance of the inter barrier layer (R b ), and lower I pass in the two test solutions compared to the smooth Ti, especially the 30nm diameter nanotubes. The corrosion resistance of the nanotubes in D-FCS was higher than in PBS because of protein adsorption from the D-FCS solution as suggested by scanning electron microscope (SEM) images. In addition, protein aggregates of 30nm diameter nanotubes caused the model of EIS spectra to transform from two-layer to three-layer. The corrosion behavior of the nanotubes for use as a dental implant material is discussed.