The interactions of UV laser beams and biotissues have been studied. The cutting quality of an ArF laser was the best sharp for hard biotissues (e.g. a bone, a tooth). From the current experiments, we found that the KrF laser beam has the highest incision ability for biological lipid of excimer lasers. For example, suet was cut off sharply by the KrF laser beam. On the other hand, the ArF laser incision has no thermal damage on suet even for the high repetition rate and the high energy fluence. However the conventional optical quartz fiber can not be available for an excimer laser beam (far-UV). So we have been investigating about UV laser power beam delivery systems. In the case of the hollow light guide with the aluminum-phosphor bronze reflector, we have obtained 56 and 75%/m transmittance of the ArF and KrF laser in straight state, respectively. Its delivery energy was 45 and 110 mJ/pulse of the ArF and KrF laser, respectively. The ArF laser transmittance has been tried in various atmosphere such as air, nitrogen, oxygen and helium. Finally, the medium of the laser delivery of the hollow light guide had better use the helium gas instead of the air. And the ArF laser transmittance and delivery energy were obtained 71%/m and 50 mJ/pulse, respectively. We have also tried the quartz fiber with OH ion doped core. The effects of a lightly doped clad with B and F on the transmittance have been investigated. In the one pulse operation, the ArF laser transmittance of B and F doped clad fiber was obtained 82%/m, which was better than that of only F doped clad fiber. The hollow light guide is suitable for the delivery system of UV laser scalpels, and the UV fiber is the useful delivery system of UV laser endoscopes.