Argon ion laser and north light fluorescent lamp photobleaching of wool destroyed chromophores absorbing in the visible wavelength region and increased modestly the number of ultraviolet absorbing chromophores. Use of north light lamps resulted in little change in the natural fluorescence of the wool. Use of the argon ion laser, however, caused a decrease in fluorescence. Irradiation with both argon ion laser and north light lamps led to yellowing. The wool yolk protected the fibers from the effects of ultraviolet radiation, but did not protect the fibers from north light irradiation.