Abstract: A method and apparatus for inducing fluorescence in human skin, in vivo, and for evaluating certain skin characteristics from the spectral intensity of induced fluorescence. The energy of a helium-cadmium laser is directed to a skin area to be evaluated by a fiberoptic element. The induced fluorescent energy having a wavelength band of interest above that of the laser wavelength, is directed to a device by a fiberoptic path for performing a spectral analysis of the fluorescent intensity. A ratio of chracteristic portions of fluorescent intensity of the skin area under test is developed and used to compare with different test subjects. The developed ratio, when taken in relation to the skin of subjects of different ages, indicates a marked difference in older subjects in comparison to that of very young subjects which correlates with long-term exposure of the skin to ultraviolet radiation.