X-ray photoelectron spectroscopy, scanning electron microscopy with energy dispersive X-ray microanalysis and X-ray diffraction were employed to study the surface chemical and electronic state, composition, morphology and structure of a biocompatible Zr-31Ti-18Nb (at%) alloy and modification of these characteristics as a result of ultrasonic impact treatment (UIT). The native oxide formed on the surface of as-prepared alloy was composed of a mixture of oxides ZrO2 (major component), TiO2, NbO2 and Nb2O5 and comprised also fine precipitates of the components' carbides and nitrides. UIT of the alloy in air for 2 min was found to cause the deformation-enhanced oxidation of the alloy components and the intense deformation-induced oxidation of carbide and nitride precipitates leading to a significant reduction of their abundance in the surface layer along with the formation of oxides, oxycarbides, oxynitrides and accumulation of amorphous carbon. In the valence band of the treated alloy, a growth of the total population of O 2p states with an appreciable increase in the abundance of bonding O 2p orbitals was observed. UIT was demonstrated to modify the composition and chemical state of both sides of the sample, with the bottom side being oxidized to a lesser extent than the top side. Also, UIT was accompanied by transfer of the pin's material to the alloy as particles similar to 100 to 700 nm in size.