TiO2 coatings were grown on Ti and Si by Atomic Layer Deposition (ALD) from titanium ethoxide and water at 300 degrees C in a wide range of the reaction cycles number N = 100-2000. TIO2 coatings were found to be amorphous at low value of N < 300 while the coatings grown at N >= 300 revealed anatase polycrystalline structure. The TiO2 coatings bioactivity was evaluated by hydroxyapatite forming ability by the technique of soaking in Simulated Body Fluid (SBF). Correlation between bioactivity and structural properties of TiO2 was determined. X-ray diffraction and scanning electron microscopy with electron probe microanalysis showed that amorphous TiO2 coating did not induce the hydroxyapatite growth whereas anatase resulted in the hydroxyapatite forming on the samples surfaces which confirmed TiO2 anatase bioactivity. Crown Copyright (C) 2011 Published by Elsevier B.V. All rights reserved.