When a biological system encounters an implant, reactions are induced at the implant-tissue interface. This article deals with various surface properties that are expected to influence tissue-implant reactions and methods available for implant surface characterization. Surface properties of interest are chemical composition, contamination and cleanliness, microarchitecture and structure, etc. Surface science offers a range of methods for surface characterization, eg, x-ray photoemission spectroscopy (XPS or ESCA) and Auger electron spectroscopy (AES), and preparation, which may be used to optimize implant fabrication with molecular level control. Examples are given from analytical and preparative work by XPS, AES, and electron microscopy on pure and alloyed titanium, with focus on surface oxides on these materials. Results of this type are valuable for basic research concerning implant-tissue reactions as well as production control and implant standardization. Schlagwörter: biomaterial surfaces, implant surfaces, surface analysis, surface preparation, titanium surface