Infrared spectroscopy and microscopy have heralded a period of rapid advances in tissue and cellular characterization during the past decade. However, vibrational spectroscopy is still an analytical tool that is neither familiar nor understood in the medical environment. For many years this field has been mainly driven by physicists and chemists, who are, undoubtedly, at the forefront of tremendous technical developments in technology, detection and data treatment. Although the theory of infrared (IR) spectroscopy is thoroughly worked out, the scientific ground of vibrational spectroscopy is now undergoing a real boost, with the application of this analytical technique in biology and biomedicine.