TiO2 thin films were prepared on NiTi surgical alloy by sol-gel method. The forming process, surface morphology and structure of the films were studied by X-ray diffraction and atomic force microscopy. The results showed that nm-scale TiO2 particles were embedded in the film of 205 nm thickness. The film existed mainly in the form of anatase, and the film was compact and smooth. The electrochemical corrosion measurement indicated that TiO2 thin film, as a protective layer, was effective for improving corrosion resistance of NiTi alloy. Additionally, in vitro blood compatibility of the film and NiTi alloy was evaluated by dynamic clotting time and blood platelets adhesion tests. The results showed that NiTi alloy coated with TiO2 film had improved blood compatibility (C) 2003 Elsevier Science B.V. All rights reserved.