Fiber optics operating in the mid-infrared offer the potential for lower losses and better tolerance to nuclear radiation than current silicate-based fibers. Moreover, mid-IR fibers may be useful for a variety of shorter-distance applications such as laser surgery, spot welding and infrared integrated optics. Although a wide array of potentially highly-transmissive mid-IR materials are available in bulk form, most are not suitable for fiber fabrication. Recently, however, a variety of new multicomponent glasses based on the fluorides of heavy metals have been developed, which may offer the best prospects to date for high performance mid-IR fibers. A critical comparison of the advantages as well as the problems associated with various prospective materials and fiber fabrication techniques is given.