Titania layers were successfully prepared on the surfaces of Ti-6Al-4V alloy via anodic oxidation in H2SO4or Na2SO4 solutions at room temperature. The titania layers consisted of pure rutile or a mixture of anatase and rutile structures after the Ti-6Al-4V alloy had been anodized in 1.0 M H2SO4 solution at 150 V or 0.5M Na2SO4 solution at 100 or 130 V. Good apatite-forming ability was demonstrated in simulated body fluid. However, surface layers with mainly titanium metallic phase or a pure anatase structure did not possess the ability to induce apatite formation. Anodic oxidation is an effective method to prepare bioactive Ti-6Al-4V alloy that can be used as an artificial bone substitute under load-bearing applications.