Abstract: The light stability of pleochroic dyes dissolved in liquid crystal colour display cellswith guest-host interactions was investigated. It was found that the decrease of absor-bance of guest-host cell is almost proportional to the exposure time and light intensity.Practical lifetime of dyes was obtained by accelerated life test. The practical lifetime ofsome anthraquinone dyes was found to be longer than 10 years. Order parameter of dyesin liquid crystal of initial and after irradiation is almost not change when absorbancechanges from A_0 to 0. 8 A_0. The relation between the molecular structure and photoche-mical stability of dyes was discussed.