To understand the apatite induction mechanism in SBF, Ca-containing titania film without CaTiO3 phase was fabricated by micro-arc oxidation (MAO) at low voltage (230 V) in an electrolytic solution containing calcium acetate monohydrate. Macro-porous, Ca-containing titania film was formed on the titanium substrate and the oxidized layer was composed of anatase and rutile phase. When immersed in 1.5SBF, no apatite was induced in the MAO specimen similar to the CaTiO3-containing titania. However, after hydrothermal treatment at 250 degrees C for 2 h, numerous precipitates, presumably calcium phosphates, were formed on the surface of the titania after 7 day immersion and titania surface was entirely covered with apatite after 14 days of immersion. This study clearly showed that Ca-containing titania has the capability to induce apatite in SBF and hydrothermal treatment plays a decisive role in apatite induction, particularly producing surface hydroxyl groups such as Ca-OH or Ti-OH. (c) 2005 Elsevier B.V. All rights reserved.