The　deformation-induced　microstructural　variation　in　the　metastable　beta-type　biomedical　Ti-35Nb-5Ta-7Zr　(wt.%)　alloy　subjected　to　multi-pass　cold-rolling　to　90%　reduction　has　been　investigated　by　a　combination　of　X-ray　diffraction,　optical　microscopy,　conventional　transmission　electron　microscopy　(TEM)　and　high-resolution　transmission　electron　microscopy　(HRTEM)　techniques.　Multi-pass　cold　rolling　for　the　Ti-35Nb-5Ta-7Zr　alloy　includes　various　localized　deformation　processes　which　can　result　in　dislocation　tangle,　stress-induced　omega-phase　transformation　and　deformation-band　formation.　Deformation-induced　amorphization　caused　by　high-density　defect　accumulation　in　deformation　bands　has　been　identified.　By　means　of　TEM　and　HRTEM　observations,　distributional,　morphological　and　structural　features　for　deformation　bands　have　been　clearly　revealed.　(C)　2011　Elsevier　B.V.　All　rights　reserved.