Advances in optical coating technology over the past decade have made it possible to produce highperformance Raman spectroscopy filters with better reliability and at lower costs. The performance and characteristics of three typical Raman filters and an ultraviolet resonance Raman filter are introduced. Some applications of surface-enhanced Raman scattering (SERS) biosensors for the detection and identification of tissues, cells, proteins, nucleic acids, drugs, and chemical pathogens are reviewed. OCIS codes: 310.6845, 240.6695, 170.5660. doi: 10.3788/COL201008S1.0196. Raman spectroscopy was first described by C.V. Raman in 1928. In recent years, it has become a useful routine tool for the analysis and study of biological and pharmaceutical samples. Raman spectroscopy uses light scattered from an excitation laser to build up a chemical fingerprint characteristic of the sample. The Raman spectrum is composed by many “sharp” lines (Raman lines). The frequency shift between the excitation light and the Raman lines is determined by the energy of the molecular vibrations, which depends on the kinds of atoms, in cluding their bond strengths and arrangements in a specific molecule. Further, it is extremely sensitive to the subtle changes in the chemistry of a sample. Since Raman spectroscopy is a technique that uses light irradiation, it can be adapted for using on a microscope. In the last few years, Raman microscopy has become apparent, coupling chemical information with microscopic scale. The new generation of confocal Raman microscopes have the capability to discriminate the area of the sample being analyzed very precisely, thus determine the chemistry of individual particles or cells. Because of these features, Raman spectroscopy has the potential to become a key biosensor for health monitoring based on molecular information. The high molecular specificity and the high content of chemical information of the technique likewise make it a very useful tool for the environmental control [1] . The main advantage of Raman spectroscopy is its capability to provide rich information about the molecular structure of the sample. Recently, sophisticated-dataanalysis techniques based on multivariate analysis made it possible to exploit the full information content of Raman spectra and draw conclusions about the chemical structure and composition of very complex systems such as biological materials. However, a great disadvantage in any applications of Raman spectroscopy comes from the extremely small scattering cross-section of the effect, resulting in very weak signals. Generally, there are two ways to enhance the sensitivity of Raman spectroscopy: developing a highly effective high-throughput optical system and inducing enhancement effect. With advances in laser technology such as narrow beam near-infrared (NIR) laser diodes, and charge-coupled device (CCD) detector technology such as open electrodes, deep depletion, and back-illuminated chip formats, especially in Raman filters and other types of optical coatings such as image antireflection (AR) and laser mirror, the sensitivity of the latest Raman microscopes enables analysis and images to be respectively done and obtained far more quickly than previously possible. In the second way, by using selected ultraviolet (UV) excitation, resonance enhancement effect can increase Raman signal by many orders of magnitude. Further, with the interaction between sample molecules and metal nanostructures in surface-enhanced Raman scattering (SERS), signals can be enhanced up to 14 orders of magnitude.