UV is a potent mutagen threatening human health. A genome analysis technology, genome profiling, was found to be used to measure UV-irradiated DNA mutations quantitatively within the range of 500J/m(2) of UVA. An intriguing phenomenon was also observed for the UV-irradiation to in vivo DNA that the apparent amount of mutations oscillated responding to an increasing amount of UV-dosage. This method is advantageous in measuring the alteration of DNA directly, eliminating the necessity of complicated interpretation required for bioassays.