Preparation of nanofibers in a core-sheath configuration, using two dissimilar materials, via a novel technique of co-axial electrospinning has presented unusual potential for use in many novel applications. The studies have addressed issues related to the technology involved and examined the suitability of the technique for producing unique nanoscale morphologies involving variety of materials. In this first major review of co-axial electrospinning, we provide details of the manufacturing and material factors affecting the process, the conditions needed for preparing desired uniform morphologies, and the different types of structures that have been successfully produced.