Possibility of multistability in exciton luminescence of organic crystals with exciton traps of different depth is shown. Annihilational multistability arises as the effect of the thermally induced escape of trapped excitons leading to a temperature rise due to the enhancement of the annihilation rate of excitons, with subsequent energy transfer to the crystal lattice. Complex hysteresis loops corresponding to multistability are calculated. It shown that quite small number of deeper exciton traps may considerably affect luminescence yield.