Optical systems based on hollow-core fiberoptics are proposed and developed for endoscopic therapy and diagnosis. A laser endoscope using a hollow optical fiber for delivery of 2.94-μm wavelength, Er:YAG laser light is useful for urology applications such as fragmentation of urinary and renal calculi. In vitro tests using a laser endoscope equipped with a hollow optical fiber show the capability for high-powered laser delivery. As an optical biopsy system for endoscopic diagnosis of tumors, a remote FTIR spectroscopy system based on hollow optical fibers is developed. Experimental results show that the system is useful for variety of in vivo spectroscopic applications.