Optical fibers have been successfully used in long-haul communication, endoscopy, and other optical systems to transmit optical power as well as information from one point to another, serving as interconnects at various scales. In integrated sensor systems, optical fibers have been frequently employed to connect the source and the detector, due to their flexibility, compactness, and low loss. However, optical fibers can provide more functions than a simple transmission channel. In this paper, we review our work on optical fibers as a platform for molecular sensors based on Raman spectroscopy (RS) and surface enhanced Raman scattering (SERS). The fibers serve to significantly increase the sensitivity of RS/SERS and to facilitate the integration of a compact sensor system. We will discuss the principles of operation of various building blocks, demonstrate our recent results, and highlight some potential applications.