Electron spectroscopy for chemical analysis (ESCA) is perhaps the most valuable single method available for characterizing the surfaces of biomaterials. The ESCA analytical method is rich in information, observes a relevant surface region, and has been shown to generate results that correlate with biological response. In this article, the analysis of actual ESCA data is illustrated by reviewing a study in which polymer-coated glass surfaces, prepared for use as tissue culture substrates, are examined by ESCA. The application of more advanced ESCA techniques such as angular-dependent analysis to this situation is also considered. Finally, published applications of ESCA to the study of polyurethanes, hydrogels, protein films, cell culture substrates, and dental materials are briefly reviewed.