Surface-enhanced Raman spectroscopy (SERS) is a promising tool in the analytical science because it provides good selectivity and sensitivity without the labeling process required by fluorescence detection. This technique consists of locating the target analyte on nanometer range of roughed Au-nanoparticles. The presence of the metal nanoparticles provides a tremendous enhancement to the resulting Raman signal through an electromagnetic enhancement of both the laser excitation light and stokes-shifted light by 5â€“6 orders of magnitudes. SERS makes it possible to create a spectroscopic device that can act as a highly sensitive molecular detector using Raman signal as a fingerprint of the analyte. In this review, we present a general overview of the recent advancements in SERS as an analytical tool for identification of molecular species with concentrations below biological level in aqueous solution, with a particular attention to its potential applications in biomedicine.