The fading rates and color changes of some monochlorotriazine dyes were examined as applied on cellophane and cotton substrates with or without dye-substrate covalent bond. The fading rates and the color changes of the dyes dyed with the covalent bond on both the substrates are less remarkable than those of the analogues dyed without the covalent bond. The covalent bond seems to play an important role in the lightfastness of reactive dyes.