The light fading reaction of 3-Methyl-1-phenyl-4-( p -diethylaminophenyl) imino-2-pyrazoline-5-one and 2-Acetamido-N-(4-dithylaminophenyl) benzoquinone monoimine in the solution containing EDTA-Fe (III) has been investigated. The light fading reaction of those dyes is remarkably accelerated by the presence of small amount of EDTA-Fe (III). The rate of the light fading reaction shows a significant dependence upon pH value of the solution and concentration of EDTA-Fe (III). It is concluded that an initiation step of the light fading reaction is due to the photoreduction from EDTA-Fe (III) to EDTA-Fe (II). The light fading reaction in a pH value of 5.4 may be expressed as follows: EDTA-Fe (III) hυ →EDTA-Fe (II) Dye+nEDTA-Fe (II) +nH⁺→HnDye (leuco dye) +nEDTA-Fe (III)