Surface-enhanced Raman scattering has recently become a powerful vibrational spectroscopic tool for numerous applications in physical, chemical, biological as well as medical science. Apart from a chemical enhancement process, plasmonic fields sustained by metal nanoparticles play a vital role in the surface enhancement phenomena. Thus most SERS based applications also involve metal nanostructures as substrates apart from the analyte molecules. High sensitivity, molecular selectivity, portability and low cost are some of the advantages of SERS over conventional spectroscopic methods that has led to its popularity. In particular, biomedical applications involving detection and sensing of biomolecules are now moving towards utilizing this new tool. This review provides an introduction of SERS for biomedical applications. The theory of SERS will be explained in the first section. A brief review on popular SERS substrates will be given in the subsequent section. The review will focus on certain biomedical applications such as glucose sensors, cancer detection and protein sensing using SERS